ROGUE

A scoundrel, rascal or unprincipled, deceitful, and unreliable person.

A mischievous scamp.

A vagrant.

Deceitful software pretending to be anti-spyware, but in fact being malicious software itself.

To cull; to destroy plants not meeting a required standard, especially when saving seed, rogue or unwanted plants are removed before pollination.

To cheat.

To give the name or designation of rogue to; to decry.

To wander; to play the vagabond; to play knavish tricks.

(of an animal, especially an elephant) Vicious and solitary.

(by extension) Large, destructive and unpredictable.

(by extension) Deceitful, unprincipled.

Mischievous, unpredictable.