extemporaneous vs offhand

extemporaneous and offhand both are adjectives.

Word	Noun	Adjective	Verb	Adverb
extemporaneous	No	Yes	No	No
offhand	No	Yes	No	Yes

As adjectives, extemporaneous and offhand are synonyms defined as:

extemporaneous and offhand: with little or no preparation or forethought

Other synonyms of extemporaneous include ad-lib, extemporary, extempore, impromptu, off-the-cuff, offhanded, unrehearsed.

extemporaneous (adjective)	offhand (adjective)
with little or no preparation or forethought	casually thoughtless or inconsiderate
	with little or no preparation or forethought

extemporaneous (adverb)	offhand (adverb)
	in a casually inconsiderate manner
	without previous thought or preparation