Standby,

Definition of Standby:

1. Passenger with a ticket but without a reservation, seeking the seat available after the confirmed reservation passengers have taken theirs.

2. Held at hand as a reserve, spare, or substitute, ready to be put to use as and when required.

Synonyms of Standby

Maecenas, Abettor, Admirer, Advocate, Aficionado, Angel, Apologist, Backer, Bit player, Buff, Champion, Defender, Dependence, Encourager, Endorser, Exponent, Extra, Fan, Favorer, Figurant, Figurante, Friend at court, Lover, Mainstay, Maintainer, Mute, Paranymph, Partisan, Patron, Promoter, Protagonist, Reliance, Second, Seconder, Sectary, Sider, Spear-carrier, Sponsor, Stalwart, Stand-in, Substitute, Supe, Super, Supernumerary, Support, Supporter, Supporting actor, Supporting cast, Sustainer, Sympathizer, Understudy, Upholder, Votary, Walk-on, Walking gentleman, Well-wisher