Origin: 1300–50; Middle English encombren < Anglo-French, Middle French encombrer, equivalent to en-en-1 + -combrer, verbal derivative of combre dam, weir < early Medieval Latin combrus < Gaulish *comberos confluence, bringing together (compare Quimper, in Brittany < Breton Kemper); see com-, bear1
early 14c., from O.Fr. encombrer "to block up," from L.L. incombrare, from in- "in" + combrus "barricade, obstacle," probably from L. cumulus "heap." Related: Encumbered; encumbering.