adjective
Definition: Having a taste that is sharp, tart, or tangy, often due to the presence of acids; can also refer to a bad mood or unpleasant demeanor.
Example: The sour lemon made my face pucker.
noun
Definition: A taste that is sharp and acidic, often associated with foods like lemons or vinegar.
Example: The sour of the lemon made the drink refreshing.
transitive verb
Definition: To change something to a taste that is sharp and unpleasant, often used in relation to food or drink.
Example: The chef decided to sour the sauce by adding vinegar.