terrific
Terrifying, causing terror; terrible; sublime, awe-inspiring.
Very strong or intense; excessive, tremendous.
Extremely good; excellent, amazing.

terrifical
Archaic form of terrific (“inspiring terror”).
terrific (superb; wonderful)

terrifick
Obsolete spelling of terrific.

terse
Of speech or style: brief, concise, to the point.
Of manner or speech: abruptly or brusquely short; curt.
Burnished, polished; fine, smooth; neat, spruce.

terser
comparative form of terse: more terse

tersest
superlative form of terse: most terse

tetraxile
tetraxonal (having four branches diverging at right angles).

therapeutic
Of, or relating to therapy.
Having a positive effect on the body or mind.

therapeutick
Obsolete form of therapeutic.

thetical
Laid down; absolute or positive, like a law.

tickable
That can be ticked; capable of being marked with a tick or check mark.
Of a bird, located so that it may be travelled to and viewed.
Of an observation, good enough to ensure correct identification and therefore allow the bird to be added to a list of observed birds.
Of a program instruction: counted for the purpose of generating periodic signals every few instructions.

ticketyboo
Alternative spelling of tickety-boo.

tidier
One who tidies.

tidiest
superlative form of tidy: most tidy

timelier
comparative form of timely: more timely

timeliest
superlative form of timely: most timely

timelike
Of a four-vector in representing a point in spacetime, having a positive or negative four-vector norm for the metric signature (+, -, -, -) and (-, +, +, +) respectively.
(of the interval between two events in spacetime) Having overlapping light cones, so that information can pass from one to the other, and one can be envisaged as a cause of the other.

timely
Done at the proper time or within the proper time limits; prompt.
Happening or appearing at the proper time.
Keeping time or measure.

timeous
In sufficient time; timely; in (its) proper time or season.

timous
Alternative spelling of timeous.

titiviller
Synonym of titivil (“mischievous gossip or troublemaker”).

titivillers
plural of titiviller

tractable
Capable of being easily led, taught, or managed.
Easy to deal with or manage.
Capable of being shaped; malleable.
Capable of being handled or touched.
Sufficiently operationalizable or useful to allow a mathematical calculation to proceed toward a solution.
Algorithmically solvable fast enough to be practically relevant, typically in polynomial time.

trafficable
Able to be trafficked or traded; marketable.
Having good trafficability: of a vehicle, able to traverse terrain; of terrain, able to support vehicle movement.

traffickable
Alternative form of trafficable.

transcendental
A transcendentalist.
Any one of the three transcendental properties of being: truth, beauty or goodness, which respectively are the ideals of science, art and religion and the principal subjects of the study of logic, aesthetics and ethics.

transcendentals
plural of transcendental

transient
Passing or disappearing with time; transitory.
Remaining for only a brief time.
Decaying with time, especially exponentially.
having a positive probability of being left and never being visited again.
Occasional; isolated; one-off
Passing through; passing from one person to another.
Intermediate.
Operating beyond itself; having an external effect.

transiso
Pertaining to a graph on a finite group whose vertices are the subgroups of a specified order and for which two vertices are adjacent if the sets of all normalized right transversals for each corresponding subgroup contain at least one common element.

transtubercular
Across or through tubercles.
Across or through tubercles.

triclinohedric
Having all the axes unequal and inclined at angles that are not right angles.

tricuspid
Having three cusps, e.g. a molar tooth
Describing the valve, between the right atrium and ventricle of the heart, that has three triangular segments

tricuspids
plural of tricuspid

triff
terrific; wonderful

trig
True; trusty; trustworthy; faithful.
Safe; secure.
Tight; firm; steady; sound; in good condition or health.
Neat; tidy; trim; spruce; smart.
Active; clever.

triggest
superlative form of trig: most trig

trirectangular
Having three right angles.

truebred
Alternative form of true-bred.
Alternative form of true-bred.
Alternative form of true-bred.

truer
comparative form of true: more true

truest
superlative form of true: most true

twerktastic
Excellent in a way involving twerking; ideal for or conducive to twerking.

twohanded
Alternative form of two-handed.

ultrafabulous
Wholly fabulous; wonderful.

ultrafine
Very fine.

ultragood
extremely good

ultraparadoxical
Relating to the third and final stage in Pavlov's theory of transmarginal inhibition, at which point negative stimulation results in positive responses and vice versa.

ultraperfect
Entirely perfect; exceptionally good.

ultraright
Extremely right-wing.

unanatomical
Not anatomical.
Not anatomically correct.

unbalanced
not balanced, without equilibrium
irrational or mentally deranged
expressing support for a certain point of view; biased
not adjusted such that debit and credit correspond
of an expression having different numbers of left and right parentheses
an offensive line with more players on one side of the center than on the other

unbeneficial
Not beneficial.

unburiable
Not ready or not proper to be buried.

uncivilised
Alternative spelling of uncivilized.

uncivilized
Not having developed a civilization.
Crude, barbarous, wild, uncultured.
Lacking good manners.

uncorrect
Uncorrected; containing errors that an editor would correct.
incorrect; wrong

underhums
plural of underhum

underinsured
not having sufficient insurance to cover loss or damage
not having proper health insurance

undernourished
Provided with insufficient nourishment to sustain proper health and growth.

understable
Of a flying disc, having a flight path curving to the right of the expected flight path.

unexcellent
Not excellent.

unexplanatory
Not explanatory; failing to offer a (good or coherent) explanation.

unfaithful
Not having religious faith.
Not keeping good faith; disloyal; not faithful.
Adulterous.
Not honest or upright.
Negligent or imperfect.
Not faithfully rendering the meaning of the source language; incorrect.

unfilial
Not befitting or proper for a son.

unfine
Not fine; shabby.

unfit
Not fit; not having the correct requirements.
Not fit, not having a good physical demeanor.
Unsuitable for a particular purpose.

unfitter
comparative form of unfit: more unfit

unfittest
superlative form of unfit: most unfit

ungood
Not good; bad.
Those who are not good; the wicked, evil, or bad.

ungooder
comparative form of ungood: more ungood (Newspeak)

ungoodest
superlative form of ungood: most ungood (Newspeak)

uninformative
lacking useful or interesting information

unipositive
Carrying one unit of positive charge.

unirritable
Not irritable; good-tempered.
Not responsive to stimuli.

unitholding
Being the owner of a beneficial interest ("unit") in a financial entity such as an investment trust.

unjocular
Not jocular; without good humour.

unjust
Not fair, just or right.

unjustified
Not justified, having no justification, unwarranted.
Not justified (of text, arranged on a page or a computer screen such that the left and right ends of all lines within paragraphs are aligned)

unmannerly
Not mannerly (“polite; having good manners”).

unmatchable
Unable to be matched.
Uniquely good; not approached by anything else in quality or excellence.

unmatchables
plural of unmatchable

unmedicinable
Not useful in medicine.
Not medicable; that cannot be treated by means of medicine.

unmeet
Not meet or proper.

unpolite
Unsophisticated, not refined; coarse, uncultured.
Lacking in good manners; impolite, discourteous.

unpositive
Not positive; negative.
Not positive; unsure.