incoming (adj.) Look up incoming at Dictionary.com
1753, "coming in as an occupant," present-participle adjective from in (adv.) + come (v.). Of game, from 1892; transferred in World War I to artillery; as a warning cry of incoming shellfire, it seems to date to the U.S. war in Vietnam (1968).
incoming (n.) Look up incoming at Dictionary.com
late 14c., "action of coming in," from incoming (adj.), which is attested from 1753. As "that which is coming in" from 1892, originally of game; transferred in World War I to artillery; as a warning cry of incoming shellfire, it seems to date to the U.S. war in Vietnam (1968).