thud vs clunk

thud and clunk both are nouns.

Word	Noun	Adjective	Verb	Adverb
thud	Yes	No	Yes	No
clunk	Yes	No	Yes	No

As nouns, thud and clunk are synonyms defined as:

Other synonyms of thud include clump, thump, thumping.

thud (noun)	clunk (noun)
a heavy dull sound (as made by impact of heavy objects)	a heavy dull sound (as made by impact of heavy objects)

thud (verb)	clunk (verb)
strike with a dull sound	make or move along with a sound as of a horse's hooves striking the ground
make a dull sound
make a noise typical of an engine lacking lubricants