tubing

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Tubes considered as a group.
• noun A system of tubes.
• noun A piece or length of tube.
• noun Tubular fabric, such as that used for making pillowcases.
• noun The activity of riding an inner tube or other inflated device for fun or relaxation, as in a stream, down a snow-covered hill, or towed behind a motorboat in a body of water.

from The Century Dictionary.

• noun Specifically, a thin steel pipe or tube used to line the bore of a deep well for water, gas, or air to prevent the bore from getting out of line or caving in, and to keep water and other foreign matter from getting into the well from the sides of the hole. It is thinner in gage than boiler-tube or pipe.
• noun The act of making tubes, or providing with tubes.
• noun A tube or tubes collectively: as, ten feet of tubing.

from the GNU version of the Collaborative International Dictionary of English.

• noun The act of making tubes.
• noun A series of tubes; tubes, collectively; a length or piece of a tube; material for tubes.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun tubes, considered as a group
• noun a length of tube, or a system of tubes
• noun the recreation of riding down a river on an inner tube
• verb Present participle of tube.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun conduit consisting of a long hollow object (usually cylindrical) used to hold and conduct objects or liquids or gases