Verb (used with object), : to abet a swindler; to abet a crime.    From Dictionary.com. 

Her firmness about going was sincere, but she had looked for more dissuasion; and this sprightly abettal of her departure seemed to leave something vacant in the ceremonies She fell singularly taciturn during supper at the Hotel Brunswick, and presently observed, "I hope I shall see Mr. Donohoe.".    From Wordnik.com.  [Lin McLean] Reference