—v., -mat•ed, -mat•ing,
1. to estimate at too high a value, amount, rate, or the like: Don't overestimate the car's trade-in value.
2. to hold in too great esteem or to expect too much from: Don't overestimate him--he's no smarter than you are.
an estimate that is too high.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.