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dejar (Verb) "to leave"
12th cent. Old Spanish lexar 'id.' In all probability, lexar represents a learned form from Latin laxare, whereas dejar comes from Vulgar Latin *daksare 'id.' (see Penny 2002; cf. Dictionnaire Étymologique Roman). From Latin laxare "to relax" with the l- replaced with d- under influence from Oscan. From the noun laxus (see laja).
Indo-European
Romance
Asturian dexar, Portuguese deixar, Galician deixar, Catalan deixar, French laisser, Italian lasciare, Aromanian lãsari, Romanian lăsare, Sardinian lassare

Roberts' (2014) theory that dejar replaced l- with d- under influence from dar fails to explain the many d-initial reflexes in Romance languages that point to a reconstructible etymon in Vulgar Latin.