The Collaborative International Dictionary of English v.0.48:

Becalm \Be*calm"\, v. t. [imp. & p. p. Becalmed (?); p. pr. &
   vb. n. Becalming.]
   1. To render calm or quiet; to calm; to still; to appease.
      [1913 Webster]

            Soft whispering airs . . . becalm the mind.
                                                  --Philips.
      [1913 Webster]

   2. To keep from motion, or stop the progress of, by the
      stilling of the wind; as, the fleet was becalmed.
      [1913 Webster]

WordNet (r) 3.0 (2006):

becalmed
    adj 1: rendered motionless for lack of wind