BIL'LOW, noun A great wave or surge of the sea, occasioned usually by violent wind. It can hardly be applied to the waves of a river, unless in poetry, or when the river is very large. BIL'LOW, verb intransitive To swell; to rise and roll in large waves, or surges.
Source: Webster's 1828 American Dictionary ↗ · public-domain · returned verbatim, no AI