lasis

Traditionally related to Latvian lāse (“drop (of liquid)”) (dialectally attested as lase, lasis), perhaps because of the drop-like little spots on a salmon's scales, from Proto-Indo-European *laḱ- (“to sprinkle, to spatter”). Another suggestion is that this term comes from Proto-Indo-European *lek- (“to jump, to leap”), referring to the mating habits of salmons, swimming and leaping upstream; but the final k leaves the s in the Baltic and Slavic forms unexplained. One would have to assume parallel forms *lek-, *leḱ- for this stem. Cognates include Lithuanian lãšis, lašiša, Old Prussian lalasso (probably a misspelled lasasso), Russian лосо́сь (losósʹ), Czech losos, Polish łosoś, Proto-Germanic *lahsaz (Old High German lahs, German Lachs, Swedish lax, English lax, lox), Tocharian B laksi (“fish”), Ossetian лӕсӕг (læsæg, “salmon”).