a medicinal or magical or poisonous beverage
"The old apothecary mixed a glowing blue potion to cure his neighbor's persistent cough."
A small portion or dose of a liquid which is medicinal, poisonous, or magical.
"The wizard carefully measured out a single potion to cure his friend's fever before swallowing it himself."
To drug.
"The assassin slipped a drugged potion into her wine to keep her from noticing him approach."