Definify.com

Webster 1913 Edition

Noun.

(Naut.)

A seaman, usually a green hand or a broken-down man, stationed in the waist of a vessel of war.

R. H. Dana, Jr.

Noun.

In ships, waisters are men who are stationed in the waist in working the ship.

waister ‎(plural waisters)

(nautical) A seaman stationed in the waist of a warship.
"The largest division of a ship's company, and the most ignoble, was that of the waisters, the men stationed in the waist, the men " without art or judgment," who hauled aft the fore and main sheets, and kept the decks white." John Masefield, Sea Life in Nelson's Time, 1905 (p. 129).