Definition of oncome:
(n) :
Advent, arrival, approach; onset.
(n) :
The commencement or initial stages of a business, especially of one which requires great exertion.
(n) :
The setting about of an action; development; progress.
(n) :
An attack; an attack or onset of a disease, fit, or episode.
(n) :
(dialectal) A mysterious disease or ailment.
(n) :
(dialectal) A heavy fall of rain or snow; cloudburst.