Ammonia is a chemical compound with the formula NH3.
Ammonia may also refer to:
- Ammonia (band), an Australian rock band
- Ammonia (genus), a widespread genus of estuarine foraminiferan
- Ammonium hydroxide, a cleaning chemical commonly referred to as ammonia
- Hera Ammonia, an epithet of Greek goddess Hera
- Ammonia, the ancient name of Mersa Matruh
- SF Ammonia, a railway ferry in Norway
- Ammonia (data page)