type of fish with a head formed to attach to objects or other fish," 1560s, from Latin remora "sucking fish," literally "delay, hindrance," from re- "back" (see re-) + mora "delay" (see moratorium); so called because the fish were believed by the ancients to have the power to retard a vessel to which they attached themselves.
Hence, in 17c.-18c., "an obstacle, an impediment" (the first sense of the word in Johnson's dictionary). The belief seems to predate the Romans: in Greek, such fishes were ekhenēis, literally "ship-holder," from ekhein "to hold" + naus (dative nei) "ship." Pliny writes that Antony's galley was delayed by one at Actium, and popular fables of the fish and its power to hold in place ships under sail circulated widely in the Middle Ages and after, from Ovid, etc. Sometimes called in English stayship or stopship.
"intense and painful self-condemnation and penitence due to consciousness of guilt; the pain of a guilty conscience," late 14c., from Old French remors (Modern French remords) and directly from Medieval Latin remorsum"a biting back or in return," noun use of neuter past participle of Latin remordere "to vex, torment disturb," literally "to bite back, bite again" (but seldom used in the literal sense), from re- "back, again" (see re-) + mordēre "to bite," which is perhaps from an extended form of PIE root *mer- "to rub away, harm."
The sense evolution was via the Medieval Latin phrase remorsus conscientiæ (Chaucer's remors of conscience, also translated into Middle English as ayenbite of inwit). Middle English also had a verb, remord "to strike with remorse, touch with compassion, prick one's conscience" (late 14c.), from Latin remordere. Richard Brome's "Merry Beggars" (1641) delighted that they had
No bargains or accounts to make,
No land or lease to let or take:
Or if we had, should that remore us
When all the world's our own before us[?]
1829, "to recollect," a back-formation from reminiscence. Meaning "indulge in reminiscences" is from 1871. "[S]omewhat colloquial" [OED] and mistrusted by the literary (in the OED's earliest citation for it, reminisce is followed immediately by an aside, "the word shall never enter my vocabulary"). Related: Reminisced. Reminiscing as a verbal noun, "action of remembering," is by 1891.
1650s, "fact of being worthy of comment," also "an act of observation" (a sense now obsolete), from remark (v.). The meaning "a verbal or written notice or comment" is from 1670s; the sense of "observation, notice" also is from 1670s.
early 15c., in law, of rights of ownership, "to devolve upon a second party," from remainder (n.). The meaning "dispose of (the remaining unsold editions of a book) at a reduced price" is by 1902, from the noun in the publication sense. Related: Remaindered.