/ ˌʌndəˈsel; NAmE ˌʌndərˈsel/ verb ( un·der·sold , un·der·sold / -ˈsəʊld; NAmE -ˈsoʊld/) [ vn ]
1.
to sell goods or services at a lower price than your competitors
2.
to sell sth at a price lower than its real value
3.
to make people think that sb/sth is not as good or as interesting as they really are :
Don't undersell yourself at the interview.