Dictionary.com was founded by Brian Kariger and Daniel Fierro as part of Lexico Publishing, which also startedThesaurus.com andReference.com.[6] At the time of its launch, it was one of the web's first in-depth reference sites.[7] In July 2008, Lexico Publishing Group, LLC, was acquired byAsk.com, anIAC company,[8][9] and renamed Dictionary.com, LLC.[10] In 2018, IAC sold Dictionary.com and Thesaurus.com toRock Holdings.[11] At the time of the sale, Dictionary.com was the 447th most trafficked website in the United States, according to the website tracking serviceSimilarWeb.[11] In 2015, they estimated that there are 5.5 billion word searches a year on its site.[12] In 2024, Rock Holdings sold Dictionary.com and Thesaurus.com to IXL Learning.[5]
In July 2025, the site deleted all user accounts and removed its ad-free Pro app.[13]
Among its features,Dictionary.com offers a Word of the Day,[14] a crossword solver,[15] and a pop culture dictionary[16] that includes emoji and slang sections.
In 2010,Dictionary.com began aWord of the Year feature with the wordchange.[17] The selection is based on search trends on the site throughout the year and the news events that drive them.[18]Dictionary.com's words of the year have been:[17]
In April 2009, they launched anapp on theApple App Store allowing users to find definitions and synonyms. It also included audio pronunciations, alphabetical indexing, and synonym example sentences.[21] Since then,Dictionary.com released a standalonethesaurus app calledThesaurus Rex along with education apps,Dictionary.com Flashcards,Word Dynamo, andLearning to Read with Zoo Animals.
In early 2020, in response toCOVID-19 quarantine home-schooling needs,Dictionary.com launched an interactive platform for learning at home, and an online tutoring service.[22] Later that yearDictionary.com's sister site,Thesaurus.com, launched a writing assistant and grammar checker calledGrammar Coach.[23] Thecoronavirus outbreak led to the addition of novel words to the main dictionary (e.g.,fomite) and the slang dictionary (e.g.,rona).[24]