UNSPORTSMANLIKE

dirty, cheating(a), foul, unsporting, unsportsmanlike

(adjective) violating accepted standards or rules; “a dirty fighter”; “used foul means to gain power”; “a nasty unsporting serve”; “fined for unsportsmanlike behavior”

Source: WordNet® 3.1

Etymology

Adjective

unsportsmanlike (comparative more unsportsmanlike, superlative most unsportsmanlike)

violating the accepted standards of sportsmanship

Synonym: unsportsmanly

Source: Wiktionary