Viridity

is read as \vuh-RID-i-tee\ and means
.................greenness; verdancy; verdure
......................youth; innocence; inexperience

Example1: The country's viridity is too obvious to be missed.
Example2: Often, it is the children's viridity that is being abused.

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Vagary

\vuh-GAIR-ee; VEY-guh-ree\ means unpredictable or erratic action, occurrence, course, or instance

Related definition: a whimsical, wild, odd or unusual idea, desire or action

Example: This group around here is indulging in other vagaries. God knows what!

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Vespertine

Read as \VES-per-tayhn; tin\ which means of, or pertaining to, or occurring in the evening.

This word is best used to describe certain flowers that open or expand in the evening or to bats and owls that are nocturnal animals.

It can also be partnered with matutinal which is the opposite of vespertine, for quick association.

dictionary.com page link for vespertine

Valetudinarian

\val-uh-too-din-AIR-ee-un; -tyoo-\ means a weak or sickly person, especially one morbidly concerned with his or her health.

I first encountered this word from one of Sherlock Holmes' stories. Though I haven't forgotten the word since I looked up its definition from a dictionary, I am including it here to share it to you. Hope you'll remember it too.

dictionary.com page link for valetudinarian