Earliest use of "rookie"? [closed]

What is the earliest use of the noun "rookie" and why has it become the most common synonym for newcomer? What were its vectors?

Solution 1:

A simple search of rookie from etymonline.com

Barrère ["A Dictionary of Slang, Jargon & Cant," 1890] has "Rookey (army), a recruit; from the black coat some of them wear," so perhaps directly from rook (n.1). Came into general use in American English during the Spanish-American War.

The rapid growth of a word from a single seed transplanted in a congenial soil is one of the curiosities of literature [your question of 'vector'] Take a single instance. A few weeks ago there was not one American soldier in a thousand who knew there was such a word as "rookey." To-day there are few soldiers and ex-soldiers who have not substituted it for "raw recruit." ["The Midland Monthly," December 1898]

From the OED

1868 Colburn's United Service Mag. We..rather disliked the other things being done away with, fancying..that they would say it was a lot of raw rookies who could not be trusted either to draw a sword or spur a horse.

Solution 2:

Rookie

[? SE recruit or children’s use rookie, a lookout, if one considers that a lookout would be the least active & and thus newest/youngest member of a gang; note crow-boy, a lookout, used in Southwark in the late 19C and derived f. the rural term for the boy who scared birds away from growing crops]

• c.1880 ‘O’Reilly’ [US army poem] He drank with all the rookies, and shoved his face as well, / The whole outfit is on the bum, / O’Reilly’s gone to Hell.

From Green’s Dictionary of Slang