yes
Grunted is typically not used as an adjective; it is the past tense of the verb grunt. However, it could be used in a descriptive way, such as "he let out a grunted response," where it is still functioning as a past tense verb.
The woman grunted in frustration.
The negative adjective of "agreeable" is disagreeable.
The negative adjective for suitable is unsuitable.
The word unusual *is* an adjective, the negative of the adjective usual.A related adjective that has a different meaning is unused, the negative of the past participle used.
They didn't really talk, but rather grunted. They grunted the same way we do now.
a negative adjective would be fat or chunky while a positive adjective meaning the same thing would be big build or heavy set.
hurked?
The adjective form of the noun queen is queenly. Related adjectives are queenlike and the negative adjective queenless.
No, it is not an adjective. The word "con" is a noun (a negative, or a convict) or a verb (to swindle).
despair
ineffective