A synapse is cholinergic if it uses acetylcholine as its neurotransmitter. The parasympathetic nervous system is entirely cholinergic.

A cholinergic agent, also known as a parasympathomimetic is a chemical which functions to enhance the effects mediated by acetylcholine in the central nervous system, the peripheral nervous system, or both. These include the acetylcholine receptor agonists muscarine and nicotine, as well as anticholinesterases.