trump vs overtrump

trump is a noun but overtrump is not a noun.

Word	Noun	Adjective	Verb	Adverb
trump	Yes	No	Yes	No
overtrump	No	No	Yes	No

As verbs, overtrump is a hyponym of trump; that is, overtrump is a word with a more specific, narrower meaning than trump:

Other hyponyms of trump include crossruff.

trump (noun)	overtrump (noun)
a playing card in the suit that has been declared trumps
a brass musical instrument with a brilliant tone; has a narrow tube and a flared bell and is played by means of valves
(card games) the suit that has been declared to rank above all other suits for the duration of the hand

trump (verb)	overtrump (verb)
proclaim or announce with or as if with a fanfare	play a trump higher than (one previously played) to the trick
get the better of
play a trump
produce a sound as if from a trumpet