keep; "She manages to hold down two jobs"

restrain; "please hold down the noise so that the neighbors can sleep"

to pin an opponent. (To achieve a hold down, control must be gained of at least one arm, and at least one shoulder must be in contact with the mat.)

To be held underwater by a wave. A two-wave hold down is to be held down while two waves pass over.

Holdown or hold-down or hold down in Structural Engineering refers to the steel device or hardware that is installed at the end of a Plywood Shear Wall. The holdowns provide uplift resistance against the overturning moment imposed on the wall due to "In-Plane" Lateral Load applied at the top of the wall.