The Collaborative International Dictionary of English v.0.48:

Impose \Im*pose"\, v. i.
   To practice tricks or deception.
   [1913 Webster]

   To impose on or To impose upon,
   (a) to pass or put a trick on; to delude; to cheat; to
       defraud. "He imposes on himself, and mistakes words for
       things." --Locke.
   (b) to place an unwelcome burden or obligation on (another
       person); as, she imposed on her friend to drive her
       daughter to school.
   (c) to take unfair advantage of (a person, a friendship); as,
       he imposed on his friendship with The Mayor to gain
       business.
       [1913 Webster +PJC]