Dictionary.net

• A frame of timber, forming a support for the spare top-masts, yards, and booms of a vessel.

1914 - Nuttall's Standard dictionary of the English language
By Nuttall, P.Austin.

• n. pl. Two strong frames, consisting of upright posts with a cross piece, placed one at the fore and the other at the main hatchway, between which the long boat, spare spars, booms, &c., are stowed.

1871 - The Cabinet Dictionary of the English Language