Source : Webster's Revised Unabridged Dictionary (1913)

Bilk \Bilk\, v. t. [imp. & p. p. {Bilked}; p. pr. & vb. n.
   {Bilking}.] [Origin unknown. Cf. {Balk}.]
   To frustrate or disappoint; to deceive or defraud, by
   nonfulfillment of engagement; to leave in the lurch; to give
   the slip to; as, to bilk a creditor. --Thackeray.