brim: [13] Brim appears out of the blue at the beginning of the 13th century, meaning ‘edge, border’, with no apparent ancestor in Old English. It is usually connected with Middle High German brem and Old Norse barmr, both ‘edge’, which would point to a prehistoric Germanic source *berm- or *barm-. It has been conjectured that this could derive from the stem *ber- (source of English bear ‘carry’), and that the etymological meaning of brim is thus ‘raised border’. The modern sense ‘rim of a hat’ is first recorded in Shakespeare. => bear
c. 1200, brymme "edge of the sea," of obscure origin, perhaps akin to Old Norse barmr "rim, brim," probably related to German bräme "margin, border, fringe," from PIE *bhrem- "point, spike, edge." (Old English had brim in the sense "sea, surf," but this probably was from the Germanic stem *brem- "to roar, rage.") Extended by 1520s to cups, basins, hats.