From Proto-Italic *palūts, possibly from Proto-Indo-European *pelH- (“pale, gray”), presumably with semantic shift "gray" > "swamp", though this is semantically tenuous. Either way, related to Latvian peļķe (“puddle”), Lithuanian pelkė (“marsh”), Sanskrit पल्वल (palvala, “pool, pond”), and possibly Ancient Greek πηλός (pēlós, “mud, earth, clay”).