oncome

Etymology 1

From Middle English oncomen, from Old English oncuman, ancuman (“to arrive, come upon, happen”), from Proto-Germanic *anakwemaną (“to come to, come at, arrive”), equivalent to on- + come. Cognate with Dutch aankomen (“to arrive”), German ankommen (“to arrive”), Swedish ankomma (“to arrive”).

verb

1. (intransitive, rare) To arrive; come to; come on.
   This said, and shaking his long dark spear, then forward he hurl'd it Into the fullround buckler of Priamides Alexander; Right thro' his glittering shield oncame the redoubtable warspear, On still advanced, throughpiercing his breastplate's various-art-work … 1844, Homerus, The Iliad, rendered in Homeric verse, by L. Shadwell
   A trip from you. Taken. . . . Then time oncame … 1999, Alfred Corn, Stake: poems, 1972-1992

Etymology 2

From Middle English oncome (“an attack”), equivalent to on- + come. Compare Old English ancuman (“to arrive, come upon, happen”). More at ancome, income.

noun

1. Advent, arrival, approach; onset
   I see the dawn or rather I feel the oncome of it. 1978, Edna O'Brien, I hardly knew you
2. The commencement or initial stages of a business, especially of one which requires great exertion.
3. The setting about of an action; development; progress.
4. An attack; an attack or onset of a disease, fit, or episode.
   On inquiry it was found that this neurosis corresponded in time with the oncome of the catamenia. 1881, American journal of obstetrics and diseases of women and children: Volume 14
   "She often has oncomes," explained Angus shortly. "But now we will tell, for though but children, we talk straighter." 1906, Appleton's magazine: Volume 7
5. (dialectal) A mysterious disease or ailment.
   This woman had acquired a considerable reputation among the ignorant by the pretended cures which she performed, especially in oncomes, as the Scotch call them, or mysterious diseases, which baffle the regular physician. 1858, Sir Walter Scott, The bride of Lammermoor
6. (dialectal) A heavy fall of rain or snow; cloudburst.
7. (of a chimney) The lower edge of a fire-clay lining piece.