use-icon

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

use-icon

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

puzzle-icon

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.

open-icon

AMERICAN HERITAGE DICTIONARY APP

The new American Heritage Dictionary app is now available for iOS and Android.

scroll-icon

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.

100-words-icon

See word lists from the best-selling 100 Words Series!

Find out more!

open-icon

INTERESTED IN DICTIONARIES?

Check out the Dictionary Society of North America at http://www.dictionarysociety.com

oc·tave (ŏktĭv, -tāv)
Share:
n.
1. Music
a. The interval of eight diatonic degrees between two tones of the same name, the higher of which has twice as many vibrations per second as the lower.
b. A tone that is eight diatonic degrees above or below another given tone.
c. Two tones eight diatonic degrees apart that are sounded together.
d. The consonance that results when two tones eight diatonic degrees apart are sounded.
e. A series of tones included within this interval or the keys of an instrument that produce such a series.
f. An organ stop that produces tones an octave above those usually produced by the keys played.
g. The interval between any two frequencies having a ratio of 2 to 1.
2. Ecclesiastical
a. The eighth day after a feast day, counting the feast day as one.
b. The entire period between a feast day and the eighth day following it.
3. A group or series of eight.
4.
a. A group of eight lines of poetry, especially the first eight lines of a Petrarchan sonnet. Also called octet.
b. A poem or stanza containing eight lines.
5. Sports A rotating parry in fencing.

[Middle English, eighth day after a feast day, from Old French, from Medieval Latin octāva (diēs), from Latin, feminine of octāvus, eighth, from octō, eight; see oktō(u) in the Appendix of Indo-European roots.]

oc·taval (ŏk-tāvəl, ŏktə-vəl) adj.

The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. 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.

This website is best viewed in Chrome, Firefox, Microsoft Edge, or Safari. Some characters in pronunciations and etymologies cannot be displayed properly in Internet Explorer.