'arch-Catholic' originates from the prefix 'arch-' (from Greek 'arkhi-' / 'archi-'), meaning 'chief' or 'principal', combined with 'Catholic' (from Greek 'katholikos', via Latin 'Catholicus'), where 'katholikos' meant 'universal'.

'arch-' came from Greek 'arkhi-'/'archi-' and was used in compounds in Medieval and Modern English; 'Catholic' entered English via Latin 'Catholicus' from Greek 'katholikos'; the modern compound 'arch-Catholic' developed by combining the prefix with 'Catholic' to describe an extreme form of adherence.

Initially the elements meant 'chief' (arch-) and 'universal' (Catholic); over time the compound evolved to mean 'extremely supportive of the Catholic Church' rather than a literal 'chief universal' sense.