bl- — de Vaan
bl- 'consisting of two, having two' [pref.] (Naev.+) Derivatives: dvi- in dvidens 'with two teeth' (Paul, ex F.) (bidens [adj.] Acc.+, bidens [mJt] Lab.+), dvicensus 'cum altero, id est, cum filio census' (Paul, ex F.\ Earliest attested cp. in bi< bipes, bipedis 'two-footed' (Naev.+). Opaque forms in *bi-: bigae, -arum 'pair of horses (rarely other animals), chariot with two horses' (Enn.+) < *dwi-jug-a- 'having two … — [de Vaan, s.v. bl-, p. 85]