starting lineup; starting member
Sports term referring to the players who start a game, or the lineup itself. Often used in baseball, soccer, basketball, etc.
See also: スターティングメンバー
Today's starting lineup has been announced.
He was selected as a starting member.
Compound of 先発 (せんぱつ, 'starting first') + メンバー ('member'). A straightforward sports term.