American Heritage Dictionary Entry: phase HOW TO USE THE DICTIONARY To look up an entry in The American Heritage Dictionary of the English Language, use the search window above. For best results, after typing in the word, click on the “Search” button instead of using the “enter” key. Some compound words (like bus rapid transit, dog whistle, or identity theft) don’t appear on the drop-down list when you type them in the search bar. For best results with compound words, place a quotation mark before the compound word in the search window. guide to the dictionary THE USAGE PANEL The Usage Panel is a group of nearly 200 prominent scholars, creative writers, journalists, diplomats, and others in occupations requiring mastery of language. Annual surveys have gauged the acceptability of particular usages and grammatical constructions. The Panelists NEED HELP SOLVING A CROSSWORD PUZZLE? Go to our Crossword Puzzle Solver and type in the letters that you know, and the Solver will produce a list of possible solutions. -- AMERICAN HERITAGE DICTIONARY APP The new American Heritage Dictionary app is now available for iOS and Android. THE AMERICAN HERITAGE DICTIONARY BLOG The articles in our blog examine new words, revised definitions, interesting images from the fifth edition, discussions of usage, and more. OPEN DICTIONARY PROJECT Share your ideas for new words and new meanings of old words! Start Sharing Now! -- See word lists from the best-selling 100 Words Series! Find out more! INTERESTED IN DICTIONARIES? Check out the Dictionary Society of North America at http://www.dictionarysociety.com phase (fāz) Share: Tweet n. 1. A distinct stage of development: “The American occupation of Japan fell into three successive phases” (Edwin O. Reischauer). 2. A temporary manner, attitude, or pattern of behavior: just a passing phase. 3. An aspect; a part: We must reconsider every phase of the operation. 4. Astronomy a. One of the cyclically recurring apparent shapes of the visibly illuminated portion of the moon or a planet. b. The relative configuration, measured in angular units such as degrees or radians, of two orbiting bodies that periodically eclipse. 5. Physics a. A particular stage in a periodic process or phenomenon. b. The fraction of a complete cycle elapsed as measured from a specified reference point and often expressed as an angle. 6. Chemistry a. Any of the forms or states, solid, liquid, gas, or plasma, in which matter can exist, depending on temperature and pressure. b. A discrete homogeneous part of a material system that is mechanically separable from the rest, as is ice from water. 7. Biology A characteristic form, appearance, or stage of development that occurs in a cycle or that distinguishes some individuals of a group: the white color phase of a weasel; the swarming phase of locusts. v. phased, phas·ing, phas·es v. tr. 1. To plan or carry out systematically by phases. 2. To set or regulate so as to be synchronized. v. intr. To become incorporeal so as to be able to move through a solid object: “He got out of the car without opening the door—just phased through it—and walked up the steps of the church” (Dean Koontz). Phrasal Verbs: phase in To introduce, one stage at a time. phase out To bring or come to an end, one stage at a time. Idioms: in phase In a correlated or synchronized way. out of phase In an unsynchronized or uncorrelated way. [Back-formation from New Latin phasēs, phases of the moon, from Greek phaseis, pl. of phasis, appearance, from phainein, to show; see bhā-1 in the Appendix of Indo-European roots.] phasic (fāzĭk) adj. The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved. Indo-European & Semitic Roots Appendices Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices: Indo-European Roots Semitic Roots The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots. 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