Tail"-bay` (?), n. 1. (Arch.) One of the joists which rest one end on the wall and the other on a girder; also, the space between a wall and the nearest girder of a floor. Cf. Case-bay.

2. The part of a canal lock below the lower gates.

Tail"-bay` (?), n. 1. (Arch.) One of the joists which rest one end on the wall and the other on a girder; also, the space between a wall and the nearest girder of a floor. Cf. Case-bay.

2. The part of a canal lock below the lower gates.