(music) the frequency of 435 hertz assigned to the A above middle C, widely used until 1939 See pitch1 (sense 30)
noun 1. a radio silence observed on vessels at sea for two three-minute periods each hour to permit distress signals to be heard.
noun 1. a branch of political science dealing with the relations between nations.
noun 1. a vocabulary of scientific and technical words, terms, formulas, and symbols that are almost universally understood by scientists and similarly used in at least two languages. Abbreviation: ISV.
- International screw thread
noun 1. (engineering) a metric system for screw threads relating the pitch to the diameter