underestimate

[1]	undervalue , underrate , discount , misjudge , miscalculate , misprize , minimize , depreciate , belittle , not do justice to , fail to appreciate , set (too) little store by , think (too) little of
[2]	undervalue
[3]	lowball
[4]	underrate

[1]	underestimation , underrating , underreckoning