Definition
An adjustable open-end wrench with a movable jaw controlled by a worm-gear screw, allowing a single tool to fit a range of nut and bolt sizes. Crescent is a brand name (Crescent Tool Company) that has become the common term for this style of wrench.
Plain English
A wrench with one fixed jaw and one sliding jaw. You turn a small worm-gear screw to open or close the jaws to match the size of the nut you're working on, so one wrench covers many sizes.
Context Anchor
Seen in aircraft maintenance, ground servicing, and tool lists where an adjustable wrench may be used on hardware.
Derivation
Named after the Crescent Tool Company of Jamestown, New York, which popularized the design in the early 1900s. The name stuck so widely that 'crescent wrench' is now used for any adjustable wrench of this style, regardless of who made it.
Why Pilots Care
Correct use prevents rounded fasteners and ensures secure connections that directly affect aircraft airworthiness.
Intuition Check
“Crescent” does not mean the wrench is mainly for curved or crescent-shaped parts. In this term, it refers to a common name for an adjustable wrench.
Example Sentence 1
He grabbed a crescent wrench from the toolbox to loosen the fuel drain fitting.
Example Sentence 2
During preflight, a crescent wrench was used to check the tightness of the battery hold-down bolts.