Nicotine (noun)

1. A colorless, oily, water-soluble, highly toxic liquid alkaloid that is the active principle of tobacco. It acts as a stimulant in small doses, but in larger amounts blocks the action of autonomic nerve and skeletal muscle cells.
2. The addictive drug found in tobacco and related products.

Origin:

From french nicotine, from latin nicotiana, named after jean nicot, the french ambassador to portugal who in the 1560s sent tobacco and seeds to france, promoting their medicinal use.

Examples:

1. Nicotine is a highly addictive substance.
2. Nicotine gum can help smokers quit by reducing cravings for cigarettes.
3. Smoking cigarettes is one of the main ways that people consume nicotine.
4. Nicotine is present in many forms of tobacco, including cigarettes, cigars, and chewing tobacco.
5. Nicotine is a stimulant that can cause increased heart rate, blood pressure, and breathing.