Avalanche
late 18th century: from French, alteration of the Alpine dialect word lavanche (of unknown origin), influenced by avaler ‘descend’; compare with Italian valanga .
wiktionary
From French avalanche, from Franco-Provençal (Savoy) avalançhe, blend of aval(“downhill”) and standard lavençhe, from Vulgar Latin *labanka (compare Occitan lavanca, Italian valanga), of uncertain origin, perhaps an alteration of Late Latin lābīna(“landslide”) (compare Franco-Provençal (Dauphiné) lavino, Romansch lavina), from Latin lābēs, from lābor(“to slip, slide”).
etymonline
avalanche (n.)
"fall or slide of a mass of snow on a mountain slope," 1763, from French avalanche (17c.), from Romansch (Swiss) avalantze "descent," altered (by metathesis of -l- and -v-, probably influenced by Old French avaler "to descend, go down," avalage "descent, waterfall, avalanche") from Savoy dialect lavantse, from Provençal lavanca "avalanche," perhaps from a pre-Latin Alpine language (the suffix -anca suggests Ligurian). Extended to falls of rock, landslides. As a verb, from 1872.
