late 17th cent. (in the sense 'cause to swell'): from obsolete bloat 'swollen, soft', perhaps from Old Norse blautr 'soft, flabby'. The noun sense dates from the late 19th centlate 16th cent.: related to the adjective bloat used in the compound bloat herring 'bloater' from the late 16th to mid 17th cent.; of obscure origin