mental vs mentum

mental is not a noun while mentum is a noun.

Word	Noun	Adjective	Verb	Adverb
mental	No	Yes	No	No
mentum	Yes	No	No	No

mental (noun)	mentum (noun)
	a projection below the mouth of certain mollusks that resembles a chin
	the protruding part of the lower jaw
	a projection like a chin formed by the sepals and base of the column in some orchids

mental (adjective)	mentum (adjective)
involving the mind or an intellectual process
of or relating to the mind
of or relating to the chin- or liplike structure in insects and certain mollusks
of or relating to the chin or median part of the lower jaw
affected by a disorder of the mind