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

tat¹

(tăt)

intr. & tr.v. tat·ted, tat·ting, tats

To do tatting or produce (something) by tatting.

[Probably back-formation from TATTING.]

tat² also TAT

(tăt)

1. A gene in the AIDS virus that stimulates the host cell to replicate genetic components of the virus.

2. The protein encoded by this gene that is a potent transactivator of viral replication.

[t(rans)a(c)t(ivator) (gene).]

tat³ or tatt

(tăt) Informal

A mark or design made on the skin; a tattoo.

tr.v. tat·ted, tat·ting, tats or tat·ted or tat·ting or tatts

To tattoo.

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.

HOW TO USE THE DICTIONARY

THE USAGE PANEL

NEED HELP SOLVING A CROSSWORD PUZZLE?

AMERICAN HERITAGE DICTIONARY APP

THE AMERICAN HERITAGE DICTIONARY BLOG

INTERESTED IN DICTIONARIES?

Indo-European & Semitic Roots Appendices