un·der·achiev·er \ˌəndərəˈchēvə(r)\noun (-s) Etymology:under (I) + achieve + -er (II) : a person and especially a student who fails to achieve his or her potential or does not do as well as expected • underachieve\¦ ̷ ̷ ̷ ̷ ̷ ̷ ¦ ̷ ̷ \intransitive verb • underachievement\¦ ̷ ̷ ̷ ̷ ̷ ̷ ¦ ̷ ̷ ̷ ̷ \noun