Yes, tube is a Scrabble word!

Verb

1. Provide with a tube or insert a tube into

2. Convey in a tube

3. Ride or float on an inflated tube

4. Place or enclose in a tube

Noun

1. Conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases

2. Electronic device consisting of a system of electrodes arranged in an evacuated glass or metal envelope

3. A hollow cylindrical shape

4. (anatomy) any hollow cylindrical body structure

5. An electric railway operating below the surface of the ground (usually in a city)