Proto-Basque: *[lamu]
Meaning: 1 day after the day after tomorrow (three days hence) 2 four days hence
Bizkaian: etzi-limo, etzi-lume, etzi-a-ramu 1, (Oñate) etzidamu 1, (arc) etzi-luma 1, (arc) etzi-ka-ramu 2
Gipuzkoan: etzi-damu-atzetik 1
High Navarrese: etzi-damu-atzetik 1, (Esteribar) etzi-damu 1
Low Navarrese: etzi-damu 1, (Larraun) etzi-amu 1
Salazarese: etzi-damu-ago 1
Lapurdian: etzi-damu 1
Baztanese: etzi-damu 1
Roncalese: etzi-damu-ago 1
Comments: The segment *[lamu] only occurs in compounds with *eci ‘day after tomorrow’, but as a separate morpheme has the initial reflex *l- (rather than the expected medial reflex *-rd- or *-rt-); subsequently the *l, now in a medial position, has shifted to /r/ or /d/ in most Bsq dialects, with original /l/ only in some Bizkaian dialects.
