130 Science Words That Start With U – Full Glossary

Science is full of fascinating words that explain the world around us, and many of these words begin with the letter U. Learning these terms helps students, researchers, and curious minds understand concepts in biology, chemistry, physics, and astronomy more clearly. The letter U brings us words like uranium, universe, ultrasound, and unicellular, each carrying its own importance in scientific discussions. When you know these words, you can read research papers with ease, answer exam questions with confidence, and even explain complex topics in simple ways to others Science Words That Start With U.

Biology Science Words Starting With U

Word	Meaning	Example
Unicellular	An organism with one cell	Yeast is a unicellular organism.
Uracil	RNA base that pairs with adenine	Uracil is present in RNA, not DNA.
Urethra	Tube carrying urine out	The urethra is part of the excretory system.
Ureter	Tube connecting kidney to bladder	The ureter helps transport urine.
Uvula	Small fleshy tissue in throat	The uvula helps with swallowing.
Urea	Nitrogen waste in urine	The body excretes urea after protein breakdown.
Uterus	Organ where embryos grow	A baby develops inside the uterus.
Umbilical	Related to the umbilical cord	The umbilical cord connects the fetus to the mother.
Ulna	One of the forearm bones	The ulna runs parallel to the radius.
Ubiquitin	Protein that marks cells for recycling	Ubiquitin controls protein breakdown.
Utricle	Part of the inner ear	The utricle helps balance the body.
Uvea	Layer in the eye with blood vessels	Inflammation of the uvea is called uveitis.
Ulcer	Open sore in tissue	A stomach ulcer can cause pain.
Urinary	Related to urine and bladder	The urinary system removes waste.

Chemistry Science Words Starting With U

Word	Meaning	Example
Uranium	Heavy radioactive element	Uranium fuels nuclear plants.
Urethane	Organic compound used in plastics	Urethane is used in foams and paints.
Ultrafiltration	Separation using tiny membranes	Ultrafiltration purifies water.
Unsaturated	Molecule with double or triple bonds	Oils are unsaturated fats.
Uptake	Absorption of substances	Cells show uptake of glucose.
Uranyl	Ion containing uranium and oxygen	Uranyl compounds appear in chemistry labs.
Ureide	Compound from urea and acids	Plants store nitrogen as ureides.
Ultraviolet	Radiation beyond visible light	The sun emits ultraviolet rays.
Univalent	Atom with one combining capacity	Hydrogen is a univalent element.
Uniformity	Consistency in chemical makeup	The uniformity of alloys ensures quality.
Uronic	Acid from sugar oxidation	Uronic acids exist in plants.
Unimolecular	Reaction involving one molecule	A unimolecular reaction is simple.
Ultracentrifuge	Machine that spins at high speed	An ultracentrifuge separates molecules.
Uranyl nitrate	Uranium chemical compound	Uranyl nitrate is used in labs.

Physics Science Words Starting With U

Word	Meaning	Example
Ultrasound	Sound waves above hearing	Doctors use ultrasound for scans.
Ultrasonic	Related to very high sound waves	Bats use ultrasonic sounds to hunt.
Ultraviolet	Light beyond violet in spectrum	Ultraviolet light helps sterilize tools.
Uniform motion	Movement at constant speed	A car in uniform motion keeps steady speed.
Unidirectional	Moving in one direction only	Electricity flows in a unidirectional path.
Unstable	Not steady, likely to change	An unstable atom may decay.
Unit	Standard measure of quantity	The volt is a unit of electricity.
Uplift force	Upward force in fluids	Balloons rise due to uplift force.
Unpolarized	Light waves in random direction	Sunlight is unpolarized before filtering.
Ultracold	Extremely low temperature	Ultracold atoms show quantum effects.
Underdamped	Oscillation with little resistance	The spring was underdamped.
Uncertainty principle	Quantum law about measurement limits	Heisenberg’s uncertainty principle defines quantum limits.
Uniform field	Field with same strength everywhere	Gravity is a uniform field near Earth.
Upthrust	Buoyant force in liquids	Ships float due to upthrust.

Astronomy Science Words Starting With U

Word	Meaning	Example
Universe	All of space and time	The universe is expanding.
Umbra	Darkest shadow during eclipse	The moon’s umbra blocks sunlight.
Ultraviolet astronomy	Study of UV radiation in space	Telescopes study stars using ultraviolet astronomy.
Uranus	Seventh planet from the sun	Uranus rotates on its side.
Uplift	Rising of Earth’s crust	Uplift forms mountains.
Unidentified object	Unknown body in space	An unidentified object was spotted by astronomers.
Ultra faint galaxy	Very dim star group	A telescope found an ultra faint galaxy.
Universal law	Law that applies everywhere	Gravity is a universal law.
Ultraviolet star	Star emitting UV radiation	The sun is also an ultraviolet star.
Uplift zone	Area of rising crust	The Himalayas are an uplift zone.
Umbriel	One of Uranus’s moons	Umbriel orbits Uranus.
Ultra deep field	Hubble telescope image	The ultra deep field showed ancient galaxies.
Universal constant	Constant value in physics	The speed of light is a universal constant.
Upward jet	Stream of material in space	The volcano showed an upward jet of gas.

Medical Science Words Starting With U

Word	Meaning	Example
Ulcer	Open sore on skin or tissue	A stomach ulcer causes pain.
Urology	Study of urinary system	Urology deals with kidney and bladder health.
Ultrasound scan	Imaging test using sound waves	The doctor ordered an ultrasound scan.
Umbilical cord	Cord connecting fetus and mother	The baby gets nutrients through the umbilical cord.
Urethritis	Inflammation of the urethra	Urethritis causes painful urination.
Urticaria	Skin rash with itchy bumps	She had urticaria after an allergy.
Ulna fracture	Break in the ulna bone	The X-ray showed an ulna fracture.
Uveitis	Inflammation of the uvea in eye	Uveitis can affect vision.
Uterine	Related to the uterus	Doctors studied uterine contractions during birth.
Urinary tract	Organs that remove urine	The urinary tract includes kidneys and bladder.
Uremia	Blood condition with excess urea	Patients with uremia need dialysis.
Urobilin	Pigment in urine color	Urobilin makes urine yellow.
Uric acid	Waste product in urine	High uric acid causes gout.
Ulnar nerve	Nerve in the arm and hand	The ulnar nerve controls hand movement.

Geology Science Words Starting With U

Word	Meaning	Example
Uplift	Rise of Earth’s crust	Mountain uplift formed the Himalayas.
Ultramafic	Rock rich in iron and magnesium	Ultramafic rocks come from Earth’s mantle.
Unconformity	Gap in geological record	Rocks show an unconformity between layers.
Underground water	Water stored under Earth	Wells draw from underground water.
Upper mantle	Layer beneath Earth’s crust	The upper mantle drives plate movement.
U-shaped valley	Valley formed by glaciers	The Alps have many U-shaped valleys.
Undercutting	Erosion beneath rock layers	Rivers cause undercutting of cliffs.
Ultrabasic rock	Rock with very low silica	Ultrabasic rocks are rare on the surface.
Unstratified	Rocks without layers	Lava flows create unstratified deposits.
Underground mining	Extraction below Earth’s surface	Underground mining brings out coal.
Unstable slope	Ground likely to slide	Heavy rain made the slope unstable.
Urban geology	Study of geology in cities	Urban geology helps plan construction.
Unroofing	Removal of rock layers	Erosion causes unroofing of granite.
Ultrabed	Very thick sediment layer	The canyon shows an ultrabed of sandstone.

Environmental Science Words Starting With U

Word	Meaning	Example
Urbanization	Growth of cities	Urbanization affects ecosystems.
Upwelling	Rising of nutrient-rich water	Upwelling supports marine life.
Unsustainable	Not environmentally safe	Unsustainable farming harms soil.
Utilization	Use of natural resources	The utilization of solar power is rising.
Urban heat island	City area warmer than rural	Urban heat islands trap heat.
Ultraviolet radiation	Energy from the sun	Too much ultraviolet radiation damages skin.
Unregulated waste	Waste without control	Unregulated waste pollutes rivers.
Underground storage	Storing waste below Earth	Hazardous waste needs underground storage.
Uncontrolled emission	Release of harmful gases	Uncontrolled emissions worsen climate change.
Universal recycling	Recycling common materials	Universal recycling programs save energy.
Upland	High land area	Farmers live in upland regions.
Urban ecology	Study of nature in cities	Urban ecology explores plants and animals in towns.
Ultrafine particles	Very tiny air pollutants	Ultrafine particles harm lungs.
Utility management	Control of public services	Utility management includes water supply.

Mathematics Science Words Starting With U

Word	Meaning	Example
Unit	Standard measure	A meter is a unit of length.
Unary	Operation with one input	A square root is a unary function.
Uniform distribution	Even spread of data	Dice show a uniform distribution.
Upper bound	Largest possible value	Ten is the upper bound here.
Unbounded	Having no limit	The graph goes to unbounded infinity.
Union	Set operation joining elements	The union of A and B is all elements.
Universal set	Set containing all elements	The universal set has every number.
Undefined	Not having value	Division by zero is undefined.
Unit circle	Circle with radius 1	The unit circle helps in trigonometry.
Upper quartile	Value at 75% of data	The upper quartile splits high values.
Unimodal	Having one peak	A unimodal graph has one maximum.
Unique solution	Only one correct answer	This equation has a unique solution.
Uniformity	Evenness or equality	The class showed uniformity in scores.
Unit vector	Vector with length 1	Direction is given by a unit vector.

Technology Science Words Starting With U

Word	Meaning	Example
USB	Universal Serial Bus, connector	The printer connects with a USB cable.
URL	Web address of a page	Every site has a URL.
User interface	Way people interact with systems	A phone’s user interface should be simple.
Uplink	Data sent from Earth to satellite	The station established an uplink.
Unmanned vehicle	Machine without a driver	A drone is an unmanned vehicle.
Ultracomputer	Very fast supercomputer	Scientists used an ultracomputer for research.
Uptime	Time a system is working	The server’s uptime was 99%.
Upgrade	Improve or replace software	The app needs an upgrade.
Unicode	Universal code for characters	Text uses Unicode for all languages.
Uninterruptible power supply (UPS)	Backup power system	A UPS keeps computers safe.
User-friendly	Easy to use	The device is user-friendly.
Ubiquitous computing	Computers everywhere in daily life	Phones show ubiquitous computing.
Utility software	Tools that support systems	Antivirus is a utility software.
Unicast	One-to-one data transmission	The server used unicast for streaming.

Mixed Science Words Starting With U

Word	Meaning	Example
Ultrastructure	Fine detail of cells seen by microscope	The ultrastructure shows organelles clearly.
Unicellular algae	Algae with one cell	Unicellular algae form plankton.
Ultralight	Extremely light material	Ultralight metals are used in aircraft.
Unregulated species	Animal not protected by law	Unregulated species risk extinction.
Universal solvent	Substance that dissolves many things	Water is the universal solvent.
Updraft	Rising current of air	An updraft lifts hot air balloons.
U-shaped curve	Graph shaped like U	The study showed a U-shaped curve.
Unstable isotope	Atom that decays over time	Carbon-14 is an unstable isotope.
Urodynamics	Study of urine flow	Urodynamics tests bladder function.
Uptake rate	Speed of absorption	Plants have high uptake rate of water.
Ultrahigh frequency (UHF)	Radio waves in short range	TVs use UHF signals.
Universal donor	Blood type O for transfusions	Type O is the universal donor.
Universal recipient	Blood type AB for transfusions	Type AB is the universal recipient.
Ultra high vacuum	Space with very low pressure	Experiments need an ultra high vacuum.

Conclusion

Science words beginning with U cover every branch of knowledge, from biology and chemistry to astronomy and earth science. By learning words like uracil, uranium, universe, and ultrasound, you gain insight into how life works, how matter moves, and how the universe expands. These words connect school lessons with daily experiences, making them both educational and practical.

A strong grasp of vocabulary helps in exams, projects, and research, but it also builds a habit of thinking scientifically. Whenever you see a new science term, remember that it is not just a word but a key to understanding the world. Expanding your glossary of science words starting with U will make your learning journey easier, richer, and far more exciting.