slouch vs posture

slouch and posture both are nouns.

Word	Noun	Adjective	Verb	Adverb
slouch	Yes	No	Yes	No
posture	Yes	No	Yes	No

As nouns, posture is a hypernym of slouch; that is, posture is a word with a broader meaning than slouch:

Other hypernyms of slouch include bearing, carriage.

slouch (noun)	posture (noun)
a stooping carriage in standing and walking	the arrangement of the body and its limbs
an incompetent person; usually used in negative constructions	characteristic way of bearing one's body
	capability in terms of personnel and materiel that affect the capacity to fight a war
	a rationalized mental attitude

slouch (verb)	posture (verb)
walk slovenly	assume a posture as for artistic purposes
assume a drooping posture or carriage	behave affectedly or unnaturally in order to impress others