a. superl. [f. BOTTOM sb. 17 + -MOST; cf. topmost.] That is at the very bottom, lowest.
1861. Sala, Tw. round Clock, 206. The bottommost round of the sporting ladder.
1880. Mrs. Parr, Adam & E., xxi. 292. To set … all the folks … bottommost side upwards.
1884. Public Opinion, 3 Oct., 427/1. We might arrive at the ‘bottommost’ lock before nightfall.
