unhearing vs deaf as a post

unhearing and deaf as a post both are adjectives.

Word	Noun	Adjective	Verb	Adverb
unhearing	No	Yes	No	No
deaf as a post	No	Yes	No	No

As adjectives, unhearing and deaf as a post are synonyms defined as:

Other synonyms of unhearing include profoundly deaf, stone-deaf.

unhearing (adjective)	deaf as a post (adjective)
totally deaf; unable to hear anything	totally deaf; unable to hear anything