'Unsportsmanlike' definitions:

Definition of 'unsportsmanlike'

(from WordNet)
adjective
Violating accepted standards or rules; "a dirty fighter"; "used foul means to gain power"; "a nasty unsporting serve"; "fined for unsportsmanlike behavior" [syn: cheating(a), dirty, foul, unsporting, unsportsmanlike]

Definition of 'Unsportsmanlike'

From: GCIDE