adjective

1. Being lower; being beneath something.

2. Under anesthesia, especially general anesthesia; sedated.

   “Ensure the patient is sufficiently under.”

adverb

1. In a way lower or less than.

2. In a way inferior to.

3. In an unconscious state.

   “It took the hypnotist several minutes to make his subject go under.”

Synonyms: below, beneath

preposition

1. In or at a lower level than.

2. As a subject of; subordinate to.

   “He served in World War II under General Omar Bradley.”

3. Less than.

Synonyms: below, beneath, underneath