| Wastewater | (Environmental Engineering) Consumed or used water from a municipality or industry that contains dissolved and/or suspended matter. |
| Weak acid | (Environmental Engineering) An acid that does not ionize completely under the conditions of interest. Examples include acetic acid, carbonic acid, and hypochlorous acid. See strong acid. |
| Wetland | (Environmental Engineering) Semi-aquatic land, that is land that is either inundated or saturated by water for varying periods of time during each year, and that supports aquatic vegetation which is specifically adapted for saturated soil conditions. |
| WebApps (Web Applications) - | (Software Engineering) any application that delivers meaningful content or functionality to end users via the Web. |
| Web engineering - | (Software Engineering) the application of software engineering principles, concepts, and methods (or adaptations of them) to the development of Web-based applications or systems. |
| White box testing - | a test case design technique that makes use of a knowledge of the internal program logic |
| Work breakdown structure (WBS) - | (Software Engineering) the set of work tasks required to build the software; defined as part of the process model |
| Work flow - | (Software Engineering) the sequence of tasks that are required to accomplish some activity or action; often (but not always) used in conjunction with software process models |
| Work product - | (Software Engineering) any cohesive and persistent information that is produced as a consequence of one or more software engineering actions of tasks |
| Wagner Fineness | (Concrete Engineering) The fineness of materials such as portland cement expressed as total surface area in centimeters per gram as determined by the Wagner turbidimeter apparatus and procedure. |