guesstimate

from WordNet (r) 3.0 (2006)

guesstimate
    n 1: an estimate that combines reasoning with guessing [syn:
         {guesstimate}, {guestimate}]
    v 1: estimate based on a calculation

from The Collaborative International Dictionary of English v.0.48

guesstimate \guess"ti*mate\ n. [from guess and estimate]
   an estimate based on little information, being little better
   than a guess.
   [PJC]

[email protected]