Tranquilizer (noun)

1. A drug that reduces anxiety and tension, or one that calms the mind and body.
2. A device or technique that reduces anxiety or tension.

Origin:

From the latin word "tranquillus" meaning peaceful, calm, and the english suffix "-izer", meaning one that causes to be.

Examples:

1. She took a tranquilizer to help her sleep.
2. The tranquilizer helped calm the agitated patient.
3. The tranquilizer had a sedative effect on the patient.
4. He needed a tranquilizer to deal with the stress of the situation.
5. The doctor prescribed a tranquilizer to help her relax.