1. (v. t.) To set to/ low a value on; to estimate below the truth.

2. (n.) The act of underestimating; too low an estimate.

belittle deprecate depreciate discount disparage make light of make little of make nothing of minimize miscalculate misestimate misjudge misprize sell short set at naught set little by shrug off think little of think nothing of underprize underrate underreckon undervalue