lever
槓 centers on a rigid bar used to apply force: a lever. The meaning is narrow and technical, referring to the simple machine.
槓 combines 木 (wood) with 貢, which likely contributes the sound. The character originally referred to a wooden lever or bar.
The left side is wood 木, and the right side 貢 looks like a heavy object being lifted. Picture a wooden lever prying up a heavy tribute 貢.
For コウ, imagine using a lever to lift a heavy coal コウ (鉱) cart: coal -> コウ, and the wooden lever does the work.
three kongs; winning hand containing three kongs
forming a kong by adding a tile drawn from the wall to a declared pung
winning hand consisting of four kongs and a pair
turning a concealed pung into an open kong by calling another player's discard
forming a four-of-a-kind by adding a self-drawn tile to an open three-of-a-kind
winning on a tile robbed from another player's kong
declaring a concealed kong; forming a concealed four-of-a-kind
forming a four-of-a-kind; declaring a kong
dora tile revealed when a player declares a kong
kong; four-of-a-kind
lever