fem. proper name, also the name of one of the Fates, from Greek Moira, literally "share, fate," related to moros "fate, destiny, doom," meros "part, lot," meiresthai "to receive one's share" (from PIE root *(s)mer- (2) "to get a share of something").
Proto-Indo-European root meaning "to get a share of something."
It is the hypothetical source of/evidence for its existence is provided by: Greek meros "part, lot," moira "share, fate," moros "fate, destiny, doom;" Hittite mark "to divide" a sacrifice; Latin merere, meriri "to earn, deserve, acquire, gain."
late 14c., "one's lot or destiny; predetermined course of life;" also "one's guiding spirit," from Old French fate and directly from Latin fata (source also of Spanish hado, Portuguese fado, Italian fato), neuter plural of fatum "prophetic declaration of what must be, oracle, prediction," thus the Latin word's usual sense, "that which is ordained, destiny, fate," literally "thing spoken (by the gods)," from neuter past participle of fari "to speak," from PIE root *bha- (2) "to speak, tell, say." Often in a bad sense in Latin: "bad luck, ill fortune; mishap, ruin; a pest or plague."
From early 15c. as "power that rules destinies, agency which predetermines events; supernatural predetermination;" also "destiny personified." Meaning "that which must be" is from 1660s; sense of "final event" is from 1768. The Latin sense evolution is from "sentence of the Gods" (Greek theosphaton) to "lot, portion" (Greek moira, personified as a goddess in Homer).
The sense of "one of the three goddesses (Clotho, Lachesis, and Atropos) who determined the course of a human life" is in English by 1580s. Their Greek name was Moirai (see above), from a verb meaning "to receive one's share." Latin Parca "one of the three Fates or goddesses of fate" (source of French parque "a Fate;" Spanish parca "Death personified; the Grim Reaper") might be from parcere "act sparingly, refrain from; have mercy upon, forbear to injure or punish" (probably here a euphemism) or plectere "to weave, plait." The native word in English was wyrd (see weird).
J'y suivais un serpent qui venait de me mordre
Quel repli de désirs, sa traîne!...Quel désordre
De trésors s'arrachant à mon avidité,
Et quelle sombre soif de la limpidité!
[Paul Valéry, from La Jeune Parque]