0 abbreviation for to be arranged, agreed, or announced: used to say that some details of an event have not yet been decided: --
1 written abbreviation for to be announced, to be arranged, to be agreed, or to be advised: used to say that details about an event or activity are not yet available and will be announced, arranged, etc. later: --
a festival featuring Dixie Chicks, James Taylor, Bonnie Raitt, other artists TBA
The memo mentioned several participants and someone referred to as "TBA," or to be announced.
The keynote address will be delivered by a guest speaker (TBA).