salmon: [13] The ancestral Indo-European word for ‘salmon’ is lax. It survives in numerous modern European languages, including German lachs, Swedish lax (whence English gravlax), Yiddish laks (source of English lox ‘smoked salmon’), and Russian losos’. The Old English member of the family was læx, but in the 13th century this was replaced by salmon, a borrowing from Anglo-Norman saumoun. This in turn went back to Latin salmō, which some have linked with salīre ‘jump’ (source of English assail, insult, salient, etc) – hence the ‘leaping’ fish.
salmon (n.)
early 13c., from Anglo-French samoun, Old French salmun (Modern French saumon), from Latin salmonem (nominative salmo) "a salmon," probably originally "leaper," from salire "to leap" (see salient (adj.)), though some dismiss this as folk etymology. Another theory traces it to Celtic. Replaced Old English læx, from PIE *lax, the more usual word for the fish (see lox). In reference to a color, from 1786.
