Pneumatic caisson (Engin.), a caisson, closed at the top but open at the bottom, and resting upon the ground under water. The pressure of air forced into the caisson keeps the water out. Men and materials are admitted to the interior through an air lock. See Lock.
Cai"tiff (?), a. [OE. caitif, cheitif, captive, miserable, OF. caitif, chaitif, captive, mean, wretched, F. chÚtif, fr. L. captivus captive, fr. capere to take, akin to E. heave. See Heave, and cf. Captive.] 1. Captive; wretched; unfortunate. [Obs.] Chaucer.