The only free and comprehensive online etymological dictionary of the Spanish language
pelleja f. (Noun) "hide," "skin"
13th cent. From Latin pellicula "piece of skin," diminutive of pellis "skin" (see piel).
Asturian pelleya, Portuguese película, French pellicule, Italian pellicola, Romanian peliculă

According to Varro (De Lingua Latina), pelliculum was a strictly rural term, never used by the educated or urbane. "In Atellan farces you may observe that rustics say they have brought home a pelliculum instead of a scortum."