Definition
A measuring and layout tool with two unequal legs: one straight leg ending in a sharp scribing point, and one curved leg shaped like an inside caliper. It is used to scribe a line parallel to the edge of a workpiece or to locate the center of cylindrical stock by referencing the curved leg against the edge while the straight leg marks the surface.
Plain English
A two-legged tool where one leg hooks against the edge of a part and the other leg scratches a mark on it. It lets you draw a line that runs parallel to the edge of a piece of metal, or find the center of a round bar.
Context Anchor
Seen in aircraft maintenance layout work, especially when marking metal before cutting, drilling, or fitting a part.
Derivation
From Greek 'Hermaphroditos,' a figure with both male and female features. The tool is named this way because it combines two different leg types — one straight (like a divider) and one curved (like an inside caliper) — in a single instrument.
Why Pilots Care
Aviation maintenance technicians use this tool when laying out repairs, patches, or replacement parts. An accurate parallel line or centerline is the starting point for a clean, airworthy fabrication; a sloppy layout leads to misaligned holes, weak repairs, or rejected work.
Intuition Check
Do not let the unusual name distract you. In this maintenance context, it simply means a caliper with two different kinds of legs.
Example Sentence 1
The technician used a hermaphrodite caliper to scribe a line one inch in from the edge of the aluminum sheet before drilling.
Example Sentence 2
After measuring the worn bushing, the mechanic transferred the dimension to the replacement part with the hermaphrodite caliper.