It's Merriam-Webster's Word of the Day for February 4th.
Today's word is diaphanus, spelled D-I-A-P-H-A-N-O-U-S.
Diaphanus is an adjective.
It's a formal word used to describe fabric of a texture so fine that one can see through it.
Diaphanous is also sometimes used figuratively to describe something characterized by extreme delicacy of form.
Here's the word used in a sentence from Harper's.
What do the words diaphanous, epiphany, fancy, phenomenon,
sycophant, emphasis, and phase all have in common?
The Greek word phaenine shows more clearly in some of these words than in others,
but it underlies all of them.
The groundwork for diaphanous was laid when phaenine, meaning to bring to light,
cause to appear, was combined with the prefix dia, meaning through.
From that pairing came the Greek diaphanase, meaning transparent,
parent of the medieval Latin word diaphanous, which is the direct ancestor of the English word.
With your word of the day, I'm Peter Sokolowski.