Unsportsmanlike
/ˌʌnˈspɔːrtsmənlaɪk/
Definition 1 of 1
Pro Tip 1/3Sports Context
Mainly used in sports to describe poor behavior by players, coaches, or fans. 
The player's unsportsmanlike taunting was criticized by the fans.
Pro Tip 2/3Negative Connotation
The word carries a negative tone, indicating disapproval of the action or person. 
Unsportsmanlike actions can tarnish an athlete's reputation.
Pro Tip 3/3Beyond Rules
It includes both violating written rules and the unwritten 'spirit' of sportsmanship. 
Refusing to shake hands after a match is considered unsportsmanlike.