coffer vs caisson

coffer and caisson both are nouns.

Word	Noun	Adjective	Verb	Adverb
coffer	Yes	No	No	No
caisson	Yes	No	No	No

As nouns, coffer and caisson are synonyms defined as:

Other synonyms of coffer include lacunar.

coffer (noun)	caisson (noun)
a chest especially for storing valuables	large watertight chamber used for construction under water
an ornamental sunken panel in a ceiling or dome	an ornamental sunken panel in a ceiling or dome
	a chest to hold ammunition
	a two-wheeled military vehicle carrying artillery ammunition