Meaning

noun marine fishes with a flattened elongated body and a sucking disk on the head for attaching to large fish or moving objects

originBorrowed from Latin remora (“delay, hindrance, passive resistance”), from the belief that the fish would attach themselves to ships and slow them down, from re- (prefix meaning ‘back, backwards’) + mora (“delay”) (from Proto-Indo-European *mere (“to delay, hinder”), from *(s)mer- (“to fall into thinking, remember; to care for”)).

Etymology from Wiktionary, CC BY-SA 3.0