Abettor n. : One who abets; an instigator of an offense or an offender.

Example:
What is the difference between Abettor and abetter?

Taxonomy
Abettor, offence, free encyclopedia, commission, search, abet, beter, bait, dogs, Scandinavian origin, bite, law term, assists, crime, abettors, exceptions, principals, absence.

Defination from the web:
Abettor (from to abet, Old French abeter, á and beter, to bait, urge dogs upon any one; this word is probably of Scandinavian origin, meaning to ... Wikisource has the text of the 1911 Encyclopædia Britannica article Abettor. ...