I. ˌəp-ˈstärt intransitive verb
Date: 14th century
: to jump up (as to one's feet) suddenly
II. ˈəp-ˌstärt noun
Date: 1555
1. : one that has risen suddenly (as from a low position to wealth or power) : parvenu ; especially : one that claims more personal importance than is warranted
2. : a start-up enterprise
• up·start ˈəp-ˈ adjective