placard vs flashcard

placard and flashcard both are nouns.

Word	Noun	Adjective	Verb	Adverb
placard	Yes	No	Yes	No
flashcard	Yes	No	No	No

As nouns, flashcard is a hyponym of placard; that is, flashcard is a word with a more specific, narrower meaning than placard:

placard: a sign posted in a public place as an advertisement
flashcard: a card with words or numbers or pictures that is flashed to a class by the teacher

Other hyponyms of placard include show bill, show card, theatrical poster, flash card.

placard (noun)	flashcard (noun)
a sign posted in a public place as an advertisement	a card with words or numbers or pictures that is flashed to a class by the teacher

placard (verb)	flashcard (verb)
publicize or announce by placards
post in a public place