Bascule \Bas"cule\, n. [F., a seesaw.]

In mechanics an apparatus on the principle of the seesaw, in which one end rises as the other falls.

Bascule bridge, a counterpoise or balanced drawbridge, which is opened by sinking the counterpoise and thus lifting the footway into the air.

Source: Webster's Revised Unabridged Dictionary (1913)