Plain English Meaning

A small machine or app that ticks at a regular speed, like a clock you can adjust faster or slower.

Full Definition

A device that produces a steady, repeating beat at a set tempo, used as a reference for keeping a constant rhythm or pace.

Context Anchor

In the Aviation Instructor’s Handbook, this word is most likely encountered in learning-theory discussions about practice, timing, and building a repeatable skill.

Derivation

From the Greek 'metron' (measure) and 'nomos' (rule or law). Literally, 'a measurer of rule' — something that measures and enforces a steady pace. Knowing this helps the reader see why it's used as an example of consistent, repeating reference.