The American Heritage Thesaurus is an educational and reference application developed by MobiSystems Inc. It is considered one of the flagship products in the Houghton Mifflin Harcourt catalog, offering advanced search and learning tools. This app combines a rich database from The American Heritage® Dictionary of the English Language and an extensive vocabulary from The American Heritage® Roget's Thesaurus.

The American Heritage® Dictionary of the English Language contains over 10,000 new words and phrases, with updated definitions in rapidly changing fields such as astronomy and biology. The dictionary also features thousands of full-color images, updated geographical entries and maps, and enhanced notes on word history, synonymy, and language variation.

The American Heritage® Roget's Thesaurus provides a wide range of synonyms, including mainstream vocabulary and colorful alternatives. It includes thousands of slang, informal, and regional words, with clear definitions guiding the user to the relevant meaning.

Tailored to professionals, students, academics, and anyone in need of a comprehensive and authoritative dictionary, the American Heritage Thesaurus is an essential tool for work and home.