\A*bet"ter\, Abettor \A*bet*tor\, n.
One who abets; an instigator of an offense or an offender.
Note: The form abettor is the legal term and also in general
      use.
Syn: {Abettor}, {Accessory}, {Accomplice}.
Usage: These words denote different degrees of complicity in
       some deed or crime. An abettor is one who incites or
       encourages to the act, without sharing in its
       performance. An accessory supposes a principal
       offender. One who is neither the chief actor in an
       offense, nor present at its performance, but accedes
       to or becomes involved in its guilt, either by some
       previous or subsequent act, as of instigating,
       encouraging, aiding, or concealing, etc., is an
       accessory. An accomplice is one who participates in
       the commission of an offense, whether as principal or
       accessory. Thus in treason, there are no abettors or
       accessories, but all are held to be principals or
       accomplices.