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.
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.
A solid compound containing water molecules combined in a definite ratio as an integral part of the crystal. Often used in combination:pentahydrate
v.hy·drat·ed, hy·drat·ing, hy·drates
v.tr.
1. To rehydrate.
2. To supply water to (a person, for example) in order to restore or maintain fluid balance:"Cold water is the fastest and safest way to hydrate an ordinary athlete"(Jane E. Brody).
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:
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.