'ammonium' originates from 'New Latin', specifically the word 'ammonium', derived from 'ammonia', which was named after the temple of Jupiter Ammon in Libya, where it was first obtained.

'ammonium' changed from the 'New Latin' word 'ammonium' and has remained largely unchanged in modern English.

Initially, it referred to the ion NH₄⁺, and this meaning has largely remained the same in modern usage.