'ammonium-containing' originates from Modern English, a compound of 'ammonium' (from New Latin 'ammonium') and the participle 'containing' (from Latin 'continēre').

'ammonium' comes from New Latin 'ammonium', ultimately from Latin 'ammonia' and Greek 'ammōnios' (named for the Egyptian god Ammon/ Amun); 'containing' derives from Old French 'contenir' and Latin 'continēre' (com- + tenēre 'to hold').

Initially the element 'ammonium' name referred to substances related to 'sal ammoniac' and the temple of Ammon; as part of this compound, the phrase has consistently meant 'having or containing ammonium' without significant semantic shift.