井桁

Etymology
Compound of, from the way that four stout wooden beams would be crossed to form the top of a wellhead, similar in shape to a tic-tac-toe board.

Noun

 * 1) a puteal: a wellhead for a water well, traditionally consisting of a wooden enclosure framed along the top, and possibly bottom, with stout wooden beams crossed at the ends
 * 2) the symbols, ＃, or ♯
 * 3) a pattern similar to the symbol #, such as the shape of the crossed beams on a beam or coffered ceiling
 * 4) a kind of  featuring such a symbol
 * 5) the number  in the argot of fishmongers
 * Possibly from the way that the character has four strokes, and the way that  also means.
 * 1) an advanced remodelling technique for the chassis of a miniature four-wheel-drive racing model, consisting of a reinforcement similar in shape to a traditional Japanese wellhead