trilemma
A circumstance in which a choice must be made between three options that seem equally undesirable.
A situation in which a choice must be made among three desirable options, only two of which are possible at the same time.
An argument containing three alternatives, jointly exhaustive either under any condition(s) or under all condition(s) consistent with the universe of discourse of that argument, that each imply the same conclusion.

trilemmas
plural of trilemma

trilepton
Any particle formed from three leptons
Used attributively for any system involving three leptons

trileptons
plural of trilepton

triopha
Any of some of the genus Triopha of colourful polycerid nudibranchs.

triplex
Having three parts; triple or threefold.
Having three parts; triple or threefold.

triplexes
plural of triplex

triseriate
Arranged in three vertical or spiral rows.

triton
the nucleus of a tritium atom, consisting of a proton and two neutrons.

tritons
plural of triton

trivia
Insignificant trifles of little importance, especially items of unimportant information; froth.
A quiz game that involves obscure facts.

trivias
plural of trivia

trochi
plural of trochus

trochisci
plural of trochiscus

trochiscus
A kind of tablet or lozenge

trochus
Any member of the genus Trochus, or more generally of the family Trochidae; in non-specialist usage, including species formerly classified in that family, particularly Tectus niloticus.

trochuses
plural of trochus

trona
An evaporite, consisting of mixture of sodium carbonate and sodium bicarbonate, Na₃HCO₃CO₃·2H₂O.

trough shells
plural of trough shell

trumpet shell
A sea snail of the genus Charonia

trypanolysis
The destruction of trypanosomes

tuba
A large brass musical instrument, usually in the bass range, played through a vibration of the lips upon the mouthpiece and fingering of the keys.
A large reed stop in organs.

tubae
plural of tuba (“a tube or tubular organ; a type of Roman military trumpet”)

tubas
plural of tuba

tulip snail
Synonym of tulip shell (Fasciolaria spp.)

tumuli
plural of tumulus

tumulus
A mound of earth, especially one placed over a prehistoric tomb; a barrow.

tumuluses
plural of tumulus

tundora
A warm-to-neutral dark gray. Nominally hex #4A4244, though also used as a name for the neutral grays #404040 and #3F3F3F.

tundoras
plural of tundora

turban snails
plural of turban snail

turbans
plural of turban

turbinella
Any of the genus Turbinella of large marine gastropods.

turbinellas
plural of turbinella

turbo
A turbine.
Clipping of turbocharger.
Clipping of turbojet.
Clipping of turbomolecular pump.

turbos
plural of turbo

turkey wing
An ark clam, Arca zebra, native to the Northwest Atlantic and Caribbean.

turnip shell
The shell of any several large, thick, spiral sea snails belonging to genus Rapa and pthers, roughly turnip-shaped.
The shell of any several large, thick, spiral sea snails belonging to genus Rapa and pthers, roughly turnip-shaped.

turnus
Papilio glaucus, the eastern tiger swallowtail, a butterfly of eastern North America.

turnuses
plural of turnus

turrid
Any sea snail of the polyphyletic family Turridae, now distributed over several other families.

turrids
plural of turrid

turrilites
plural of turrilite

turritella
Any sea snail of the genus Turritella (or allied genera) of spiral marine gastropods with an elongated, turreted shell.

turritellas
plural of turritella

tusk shell
Any of the marine mollusks of the class Scaphopoda, which resemble elephant tusks.

tusk shells
plural of tusk shell

tusks
plural of tusk

typhos
Obsolete form of typhus.

typhus
Any of several similar diseases, characterised by high recurrent fever, caused by Rickettsia bacteria. Not to be confused with typhoid fever.

typhuses
plural of typhus

uber
Super; high-level; high-ranking.

ubers
plural of uber

umbracula
plural of umbraculum

umbraculum
Any umbrella-shaped appendage, such as the cap borne on the seta of Marchantia.
A place giving shelter; a pavilion, a summerhouse, etc.

umbrella
A cloth-covered frame used for protection against rain or sun.
Anything that provides similar protection.
Anything that provides similar overarching coverage of a range of concepts, purposes, groups, etc.
A strategy in which five players in the offensive zone form an umbrella-shaped formation around the opposition's goal net.
The main body of a jellyfish, excluding the tentacles.
An umbrella-shaped reflector with a white or silvery inner surface, used to diffuse a nearby light.

umbrellas
plural of umbrella

umbrello
An outdoor structure providing shade above a seat.
Obsolete form of umbrella.

umbrelloes
plural of umbrello

umbrellos
plural of umbrello

unicorn
A mythical horse, widely believed to exist until the 17th century, with a single, straight, spiraled horn projecting from its forehead.
In various Bible translations, used to render the Latin unicornis or rhinoceros (representing Hebrew רְאֵם): a reem or wild ox.
Certain animals:
Certain animals:
Certain animals:
Certain animals:
Certain animals:
A howitzer.
Someone or something that is rare and hard to find.
Someone or something that is rare and hard to find.
Someone or something that is rare and hard to find.
Someone or something that is rare and hard to find.
Someone or something that is rare and hard to find.
Being many (especially pastel) colours; multicoloured.
A 15th-century Scottish gold coin worth 18 shillings, bearing the image of a unicorn.

unicorns
plural of unicorn

unio
Any of the genus Unio of freshwater mussels

unios
plural of unio

unis
plural of uni

uranalysis
Analysis of the urine.

urinalysis
The comprehensive analysis of urine.

utriculi
plural of utriculus

utriculus
Alternative form of utricle.

vaginula
A little sheath, such as that about the base of the pedicel of most mosses.

vaginulae
plural of vaginula

vaginulas
plural of vaginula

vaginule
Alternative form of vaginula.

vaginules
plural of vaginule

valve snail
Any snail of the genus Valvata.

valve snails
plural of valve snail

vampire squid
Any extant or extinct squid-like cephalopod in the order Vampyromorphida.
Any extant or extinct squid-like cephalopod in the order Vampyromorphida.

vampire squids
plural of vampire squid

varicella
chicken pox
Any of various other eruptive diseases, such as swinepox, hives, and varioloid.

varicellae
plural of varicella

varicellas
plural of varicella

varicones
plural of varicone

vascula
plural of vasculum

vasculum
A container used by botanists to store newly-collected samples.

vasculums
plural of vasculum

vasospasmolysis
vascular spasmolysis

vega
An open tract of ground; a plain, especially one which is moist and fertile, such as those used for growing tobacco.

vegas
plural of vega

ventriculi
plural of ventriculus

ventriculus
A digestive cavity such as a gizzard or stomach.

venus
Any of the bivalve molluscs in the genus Venus or family Veneridae.

venuses
plural of venus

vermeti
plural of vermetus

vermetus
Any of the many species of marine gastropods belonging to Vermetus and allied genera, of the family Vermetidae.

vertigo
A sensation of whirling and loss of balance, caused by looking down from a great height or by disease affecting the inner ear.
A disordered or imbalanced state of mind or things analogous to physical vertigo; mental giddiness or dizziness.
The act of whirling round and round; rapid rotation.
A snail of the genus Vertigo.

vertigoes
plural of vertigo

vertigos
plural of vertigo

vesica
A bladder, especially the urinary bladder or the gall bladder.
The vesica piscis or oval aureole in mediaeval painting.

vesicae
plural of vesica

vesicas
plural of vesica

vexil
A vexillum.
A flag, a vexillum.

vexilla
plural of vexillum

vexillum
A flag, banner, or standard.
A company of troops serving under one standard.
The sign of the cross.
The upper petal of a papilionaceous flower.
The rhachis and web of a feather taken together.

vexils
plural of vexil

vidtapes
plural of vidtape