Câis'son, n.
(Synop., § 130), n. [Fr. caisson, from caisse, case, chest. See CASE.]
Sense 1. (Mil.) (a.) A chest containing ammunition; also the wagon or tumbril in which military stores are conveyed. (b.) A chest filled with explosive materials to be laid in the way of an enemy, as under some work at the possession of which he is aiming, and to be fired when he is exposed to its effect.
Sense 2. (Arch.) (a.) A wooden box or frame of strong timbers, used for laying the foundations of a bridge in situations where the coffer-dam can not be employed. (b.) A panel sunk below the surface, in flat or vaulted ceilings, or in soffits generally. Weale.
