What is the etymology of the word "snooker"

A check on OED

snooker

1889, the game and the word said to have been invented in India by British officers as a diversion from billiards. The name is perhaps an allusion (with reference to the rawness of play by a fellow officer) to British slang snooker "newly joined cadet" (1872). Tradition ascribes the coinage to Col. Sir Neville Chamberlain (not the later prime minister of the same name), at the time subaltern in the Devonshire Regiment in Jubbulpore.

and word origins

The most widely canvassed theory of the origins of the term snooker is that it is an adaptation of late 19th-century army slang snooker ‘new cadet’ (‘These embryo generals were called by the somewhat sneering terms of “snookers” or “last-joined”,’ Routledge’s Every Boy’s Annual 1872)... The ancestry of snooker (to mean) ‘new cadet’, however, remains a mystery.

The online etymology dictionary suggests it derives from a slang term for "newly joined cadet" http://www.etymonline.com/index.php?term=snooker

So, yes, that would seem to be true.