From WordNet (r) 2.0 (August 2003) [wn]:
jerk-off
n : terms of abuse for a masturbator [syn: tosser, wanker]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
jerkoff \jerk"off\, a.
A lazy, foolish, stupid, or otherwise contemptible person; --
an offensive and disparaging term. [vulgar slang]
Syn: jerk.
[PJC]