witless vs nitwitted

witless and nitwitted both are adjectives.

Word	Noun	Adjective	Verb	Adverb
witless	No	Yes	No	No
nitwitted	No	Yes	No	No

As adjectives, witless and nitwitted are synonyms defined as:

witless and nitwitted: (of especially persons) lacking sense or understanding or judgment

Other synonyms of witless include senseless, soft-witted.

witless (adjective)	nitwitted (adjective)
(used as complement) to the utmost degree	(of especially persons) lacking sense or understanding or judgment
(of especially persons) lacking sense or understanding or judgment