have a loose screw
Definition of have a loose screw
: to be crazy You've got to have a loose screw to think that's a good idea. You've got to have a few loose screws to think that's a good idea.
Word by Word Definitions
: a simple machine of the inclined plane type consisting of a spirally grooved solid cylinder and a correspondingly grooved hollow cylinder into which it fits
: a nail-shaped or rod-shaped piece with a spiral groove and a slotted or recessed head designed to be inserted into material by rotating (as with a screwdriver) and used for fastening pieces of solid material together
: a screwlike form : spiral
: to attach, fasten, or close by means of a screw
: to unite or separate by means of a screw or a twisting motion
: to press tightly in a device (as a vise) operated by a screw
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