early 15c., "action or process of making a ship secure in a particular place by means of anchors, cables, etc.," verbal noun from moor (v.). From 1775 as "place where a vessel can be moored" (compare moorings).
"to fasten (a ship) in a particular location by or as by cables, anchors, etc.," late 15c., probably related to Old English mærels "mooring rope," via unrecorded *mærian "to moor," or possibly borrowed from Middle Low German moren or Middle Dutch maren "to moor," from West Germanic *mairojan. Related: Moored, mooring. French amarrer is from Dutch.