Sipper (noun)

1. A person or thing that drinks, especially in small sips.
2. A device, such as a straw, used to drink liquids.

Origin:

From the middle english word "sippen" meaning "to drink in small sips".

Examples:

1. She was a slow sipper of her tea.
2. The baby was a messy sipper of his milk.
3. He was a sipper of fine wines.
4. The sipper was designed for people with difficulty swallowing.
5. The sipper on the water bottle made it easy to drink while running.