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

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

per·pen·dic·u·lar (pûr′pən-dĭkyə-lər)
Share:
adj.
1. Mathematics Intersecting at or forming right angles.
2. Being at right angles to the horizontal; vertical. See Synonyms at vertical.
3. often Perpendicular Of or relating to a style of English Gothic architecture of the 1300s and 1400s, characterized by the use of fan vaulting and broad windows with many mullions.
adv.
In a perpendicular position.
n.
1. Mathematics A line or plane perpendicular to a given line or plane.
2. A perpendicular position.
3. A device, such as a plumb line, that is used in marking the vertical from a given point.
4. A vertical or nearly vertical line or plane.
[Middle English perpendiculer, from Old French, from Latin perpendiculāris, from perpendiculum, plumb line, from perpendere, to weigh carefully : per-, per- + pendere, to weigh; see (s)pen- in the Appendix of Indo-European roots.]
per′pen·dic′u·lari·ty (-lărĭ-tē) n.
per′pen·dicu·lar·ly adv.
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.

American Heritage Dictionary Products