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

res·pi·ra·tion

(rĕs′pə-rāshən)

a. The action or process of inhaling and exhaling; breathing. Also called ventilation.

b. An act of inhaling and exhaling; a breath.

2. The action or process by which an organism without lungs, such as a fish or plant, exchanges gases with its environment.

a. The oxidative process occurring within living cells by which the chemical energy of organic molecules is converted in a series of metabolic steps into usable energy in the form of ATP, involving the consumption of oxygen and the production of carbon dioxide and water as byproducts.

b. Any of various analogous metabolic processes by which certain organisms, such as anaerobic bacteria and some fungi, obtain energy from organic molecules without consuming oxygen.

res′pi·ration·al adj.

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.

American Heritage Dictionary Products

HOW TO USE THE DICTIONARY

THE USAGE PANEL

AMERICAN HERITAGE DICTIONARY APP

THE AMERICAN HERITAGE DICTIONARY BLOG

INTERESTED IN DICTIONARIES?

Indo-European & Semitic Roots Appendices

American Heritage Dictionary Products