'haitch' originates from English (dialectal), specifically as a variant of the name of the letter 'H', where it was formed by analogy and reanalysis of the traditional name 'aitch'.

'haitch' changed from the English name 'aitch' (itself reflecting Old French 'ache' for the letter H) and eventually appeared as the dialectal form 'haitch' in some English varieties (e.g., parts of Ireland and northern England).

Initially, it meant 'the name of the letter H' and it has retained that meaning; the change is primarily phonetic/orthographic rather than semantic.