Final answer:
A drug stimulating an acetylcholine receptor is a cholinergic or parasympathomimetic drug. These drugs increase parasympathetic activity by mimicking the action of acetylcholine at muscarinic receptors.
Step-by-step explanation:
A drug that causes stimulation of a receptor for acetylcholine would be classified as a cholinergic drug. These drugs mimic the action of acetylcholine, which is a neurotransmitter associated with the parasympathetic nervous system. Specifically, when a drug binds to and stimulates the muscarinic receptors just as acetylcholine would, it is known as a muscarinic agonist or parasympathomimetic drug. Consequently, such a drug would increase parasympathetic system activity. On the other hand, anticholinergic drugs block muscarinic receptors, thus inhibiting the effects of the parasympathetic nervous system. Adrenergic drugs interact with the sympathetic nervous system by binding to adrenergic receptors, affecting sympathetic responses rather than cholinergic responses.