tournament vs tourney

tournament and tourney both are nouns.

Word	Noun	Adjective	Verb	Adverb
tournament	Yes	No	No	No
tourney	Yes	No	Yes	No

As nouns, tournament and tourney are synonyms defined as:

tournament and tourney: a sporting competition in which contestants play a series of games to decide the winner

tournament (noun)	tourney (noun)
a sporting competition in which contestants play a series of games to decide the winner	a sporting competition in which contestants play a series of games to decide the winner
a series of jousts between knights contesting for a prize

tournament (verb)	tourney (verb)
	engage in a tourney