flexible vs elastic

flexible is not a noun while elastic is a noun.

Word	Noun	Adjective	Verb	Adverb
flexible	No	Yes	No	No
elastic	Yes	Yes	No	No

As adjectives, flexible and elastic are synonyms defined as:

Other synonyms of flexible include pliable, pliant.

flexible (noun)	elastic (noun)
	a fabric made of yarns containing an elastic material
	a narrow band of elastic rubber used to hold things (such as papers) together

flexible (adjective)	elastic (adjective)
able to flex; able to bend easily	capable of resuming original shape after stretching or compression; springy
capable of being changed	able to adjust readily to different conditions
making or willing to make concessions
able to adjust readily to different conditions
bending and snapping back readily without breaking