MEANING: noun: A congenial companion.
adjective: Enthusiastically friendly.

ETYMOLOGY: Short for the former greeting “Hail-fellow well met.” Earliest documented use: 1577.

HALL-FELLOW - patrols the school corridors while class is in session

HAIL-FERLOW - how an orthographically-challenged soldier exults over his week-end pass

HAIL (bellow) - dialog and stage directions for a bit part in Julius Ceasar

HAIR-FELLOW - tonsorial expert (Both terms have fallen from the modern vocabulary in favor of the shorter "barber".)