'matter-of-fact' originates from English, specifically the phrase 'matter of fact', where 'matter' comes from Middle English 'matere' (from Old French 'matiere' and Latin 'materia') meaning 'substance, topic', and 'fact' comes from Latin 'factum' meaning 'a thing done' or 'deed'.

'matter of fact' appeared in Middle English in constructions like 'matere of feit' and later developed into the hyphenated adjectival compound 'matter-of-fact' in modern English to describe a manner or attitude.

Initially, it referred simply to the 'subject' or 'thing' of fact ('matter' + 'fact'); over time it evolved into describing an unemotional, factual manner—'concerned with facts' rather than feelings.