ADJECTIVE (2)

1. of members of a team; not substitutes;

2. being a regular member of a team;
- Example: "first-string players"

The Collaborative International Dictionary of English v.0.48:

first-string \first-string\ adj.
   First to play in a game; not reserved as a substitute; -- of
   members of a team. Also used in non-sports contexts to mean
   first-rate.
   [WordNet 1.5 +PJC]

WordNet (r) 3.0 (2006):

first-string
    adj 1: of members of a team; not substitutes
    2: being a regular member of a team; "first-string players"