sconce
A type of small fort or other fortification, especially as built to defend a pass or ford.
No sconce or fortress of his raising was ever known either to have been forced, or yielded up, or quitted.
A hut for protection and shelter; a stall.
obsolete
one that […] must raise a sconce by the highway and sell switches
A squinch.
A fragment of a floe of ice.
Just then, a broad sconce-piece or low water-washed berg came driving up from the southward. The thought flashed upon me of one of our escapes in Melville Bay; and as the sconce moved rapidly close alongside us, McGary managed to plant an anchor on its slope and hold on to it by a whale-line.
Where it comes from
Borrowed from Middle Dutch schans, cognate with German Schanze.
Adapted from the Wiktionary entry sconce (CC BY-SA 4.0).