Pronounced: aye-DEH-tick, adj
Notes: I usually only hear the phrase ‘eidetic memory’, so I wasn’t sure what this word actually meant by itself.
The word quincentenary means, as a noun, “a 500th anniversary”; as an adjective, it means “of or relating to a 500th anniversary”.
Background / Comments
This word has a mixed heritage: quinque (five) in from Latin, combined with the English word centenary (100 years)
This word showed up in the late 1800s.