Ache may refer to:

• Ache (album), a You've Got Foetus on Your Breath album
• Ache (sensation), an unpleasant sensation
• The American College of Healthcare Executives (ACHE)

The Aché (also known by the hostile names Guayakí, Guaiaqui, Guoyagui, Guayaki, which literally mean rabid or ferocious rats; and the alternate spellings Ache or Axe meaning in their language human or person) are an indigenous people who lived in the subtropical forest of Eastern Paraguay as fulltime hunters until the 1970s, when they were confined to reservations. They have been the subject of anthropological research by Pierre Clastres.

In biochemistry, cholinesterase is an enzyme which catalyzes the hydrolysis of the neurotransmitter acetylcholine into choline and acetic acid, a reaction necessary to allow a cholinergic neuron to return to its resting state after activationoun