Penicillin (noun)

1. A substance obtained from a mold of the genus Penicillium, used as an antibiotic.
2. A group of antibiotics derived from the Penicillium fungus, used to treat bacterial infections.

Origin:

From the name of sir alexander fleming + -in.

Examples:

1. Penicillin was the first successful antibiotic.
2. Doctors used penicillin to treat infected wounds.
3. Penicillin is effective against a wide range of bacteria.
4. The patient was allergic to penicillin.
5. Penicillin revolutionized medicine by making it possible to treat bacterial infections.