The Collaborative International Dictionary of English v.0.48:

Perpend \Per*pend"\, v. t. [L. perpendere, perpensum; per +
   pendere to weight.]
   To weight carefully in the mind. [R.] "Perpend my words."
   --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Perpend \Per*pend"\, v. i.
   To attend; to be attentive. [R.] --Shak.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

23 Moby Thesaurus words for "perpend":
   be abstracted, brood, chew the cud, consider, contemplate, debate,
   deliberate, digest, excogitate, introspect, meditate, mind, muse,
   play around with, play with, ponder, reflect, ruminate, speculate,
   study, think over, toy with, weigh