Meaning
Usage

expressed without words

Example: I interpreted my parents’ refusal to talk as a tacit acceptance of my request.

incidental, peripheral, divergent

Example: I tried to discuss my salary, but the boss kept veering off into tangential topics.

dull, boring

Example: As time passed and the history professor continued to drone on and on, the lecture became increasingly tedious.

moderation in action or thought

Example: Maintaining temperance will ensure that you are able to think rationally and objectively.

having little substance or strength

Example: Your argument is very tenuous, since it relies so much on speculation and hearsay.

timid, fearful

Example: When dealing with the unknown, timorous Tallulah almost always broke into tears.

one who flatters in the hope of gaining favors

Example: The other kids referred to the teacher’s pet as the Tenth Grade Toady.

lethargic, dormant, lacking motion

Example: The torpid whale floated, wallowing in the water for hours.

winding

Example: The scary thing about driving in mountains are the narrow, tortuous roads.

"Tranquil" - (adjective) 

calm
Example: There is a time of night when nothing moves and everything is tranquil.

passing through briefly; passing into and out of existence

Example: Because virtually everyone in Palm Beach is a tourist, the population of the town is quite transient.

a grossly inferior imitation

Example: According to the school newspaper’s merciless theater critic, Pacific Coast High’s rendition of the musical Oklahoma was a travesty of the original.

"Trenchant" - (adjective) 

effective, articulate, clear-cut

Example: The directions that accompanied my new cell phone were trenchant and easy to follow.

not original, overused

Example: Keith thought of himself as being very learned, but everyone else thought he was trite because his observations about the world were always the same as David Letterman’s.

to shorten by cutting off

Example: After winning the derby, the jockey truncated the long speech he had planned and thanked only his mom and his horse.

depravity, moral corruption

Example: Sir Marcus’s chivalry often contrasted with the turpitude he exhibited with the ladies at the tavern.

not inclined to talk

Example: Though Jane never seems to stop talking, her brother is quite taciturn.

equivalent in value or significance

Example: When it comes to sports, fearing your opponent is tantamount to losing. 

audacity, recklessness

Example: Tom and Huck entered the scary cave armed with nothing but their own temerity.

able to be defended or maintained

Example: The department heads tore down the arguments in other people’s theses, but Johari’s work proved to be quite tenable.