From French dialectal 'lavanche,' influenced by 'avaler' (to descend), possibly from a pre-Roman Alpine language — an Alpine-born word.
A large mass of snow, ice, and rock falling rapidly down a mountainside.
From French avalanche, altered (by association with avaler, to descend, to swallow) from earlier lavanche, from Franco-Provençal lavantse, from Vulgar Latin *labanca, probably from pre-Roman Alpine *laba (a slide, a slope), possibly connected to Latin lābī (to slip, to slide, to fall), from PIE *leh₁b- (to hang loosely, to be slack, to slip). The word's journey is itself an avalanche of linguistic layers: a pre-Roman Alpine substrate word was Latinised, then passed through Franco-Provençal into French, where it was reshaped by folk etymology. The initial l- was reinterpreted as the French article