| Term | Definition |
| Y | A "Y" shaped plumbing fitting. |
| Y Strainer | A device in the shape of a Y for withholding foreign matter from a flowing liquid or gas. |
| Y-Axis | One of the axes in a three-dimensional system, that is not the x- or y-axis. |
| Yard | 1. A unit of linear measure equal to 3 feet or 36 inches; equal to 0.9144 meters. 2. A square yard, as in yards of carpeting. 3. A cubic yard, as in yards of earth cut or fill. 4. A piece of enclosed ground. 5. The space around a residence; see Curtilage. |
| Yard lumber | Run of the mill lumber in a lumber yard, including all sizes and patterns. |
| Yard of concrete | One cubic yard of concrete is 3' X 3' X 3' in volume, or 27 cubic feet. One cubic yard of concrete will pour 80 square feet of 3 ½" sidewalk or basement/garage floor. |
| Yarn Size | Carpet yarn is measured by the number of yards in length to the ounce of weight in a single ply; two to four plies of this single strand will be twisted to form the best balance for any particular weave and quality of fabric desired; it is necessary to kn |
| Yellow Fir | Douglas Fir. |
| Yellow Metal | Muntz metal. |
| Yellow Ochre | An earthy pigment made from impure iron ore, used in paint. |
| Yellow Ware | A yellow semi-vitreous ware or an earthenware with a colorless clear glaze. |
| Yellowing | Development of yellow color or cast, in whites, on aging. |
| Yield | 1. The ratio of the net income of a real estate or other investment compared to the acquisition and operating costs. 2. The amount of concrete produced by a given combination of materials; the total weight of ingredients divided by the unit weight of the |
| Yield Point | The point at which a material deforms with no increase in load; the stress at which a material ceases to deform in a fully elastic manner. |
| Yield Strength | The specified minimum yield strength or yield point of reinforcement in psi. |
| Yoke | The location where a home's water meter is sometimes installed between two copper pipes, and located in the water meter pit in the yard. |
| Yoke Vent | A pipe connecting upward from a soil or waste stack to a vent stack for the purpose of preventing pressure changes in the stacks. |
| Young's Modulus | The ratio of the unit stress to the unit strain below the proportional limit. |