Present participle of coach - to train or instruct someone in a particular skill or activity. To give guidance and support to help someone improve their performance.
From 'coach', originally a large carriage from Hungarian 'kocsi' (from Kocs, a town where such carriages were made). The meaning of 'instructor' developed from the idea that a coach 'carries' students through their learning journey.
The metaphorical leap from 'vehicle' to 'teacher' in the word 'coach' is brilliant - both carry people from one place to another, whether physically or intellectually. This transportation metaphor for education appears in many languages, showing how universal the concept of guided movement toward a goal is.
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