1570s, Nemesis, "Greek goddess of vengeance, personification of divine wrath," from Greek nemesis "just indignation, righteous anger," literally "distribution" (of what is due), related to nemein "distribute, allot, apportion one's due," from PIE root *nem- "assign, allot; take." The notion is "divine allotment to everyone of his share of fortune, good or bad." With a lower-case -n-, in the sense of "retributive justice," attested from 1590s. General sense of "anything by which it seems one must be defeated" is by 1930.
It forms all or part of: agronomy; anomie; anomy; antinomian; antinomy; astronomer; astronomy; autonomous; autonomy; benumb; Deuteronomy; economy; enumerate; enumeration; gastronomy; heteronomy; innumerable; metronome; namaste; nemesis; nimble; nim; nomad; nomothetic; numb; numeracy; numeral; numerator; numerical; numerology; numerous; numismatic; supernumerary; taxonomy.
It is the hypothetical source of/evidence for its existence is provided by: Greek nemein "to deal out," nemesis "just indignation;" Latin numerus "number;" Lithuanian nuoma "rent, interest;" Middle Irish nos "custom, usage;" German nehmen "to take."