WordNet (r) 3.0 (2006):

size up
    v 1: to look at critically or searchingly, or in minute detail;
         "he scrutinized his likeness in the mirror" [syn: size
         up, take stock, scrutinize, scrutinise]

Moby Thesaurus II by Grady Ward, 1.0:

79 Moby Thesaurus words for "size up":
   appraise, appreciate, assay, assess, autopsy, calculate, calibrate,
   caliper, canvass, check, check a parameter, check out, check over,
   check up on, compute, contemplate, dial, divide, estimate,
   evaluate, examine, eye, fathom, gauge, give an examination,
   give the eye, give the once-over, go over, graduate, hard look,
   inspect, leer, leer at, look at, look over, measure, mensurate,
   mete, meter, monitor, observe, ogle, ogle at, overhaul, overlook,
   pace, pass over, pass under review, peer at, peruse, plumb, pore,
   pore over, postmortem, prize, probe, quantify, quantize, rate,
   review, run over, scan, scrutinize, set an examination, size,
   sound, span, step, study, survey, take a long, take a reading,
   take stock of, take the measure, triangulate, valuate, value, vet,
   weigh