Featured
Games
Cultural
Writing tips

Thesaurus.com

Dictionary.com

Synonyms & Antonyms

Related Words

testing agent

NOUN

litmus paper

Synonyms

WEAK

indicator reagent

Related Words

Words related to testing agent are not direct synonyms, but are associated with the word testing agent. Browse related words to learn more about word associations.

litmus paper

Word of the Day

scuttlebutt

[skuht-l-buht]

Over 500,000 expert-authored dictionary and thesaurus entries

Entry list Careers Contact us Help Cookies, terms & privacy

IXL Learning's Dictionary Media Group reaches over 500,000,000 learners each year

Comprehensive resource for word definitions and usage

Adaptive learning for English vocabulary

Fun daily word games

English dictionary and learning for Spanish speakers

Spanish-English dictionary, translator, and learning

French-English dictionary, translator, and learning

Immersive learning for 25 languages

Comprehensive K-12 personalized learning

Marketplace for millions of educator-created resources

35,000+ worksheets, games, and lesson plans

Fun educational games for kids

Trusted tutors for 300+ subjects

Math games and learning resources for kids

© 2026 Dictionary Media Group, Inc., a division of IXL Learning

by dictionary.com

Join 12,000,000 vocabulary learners

Start learning new words today on VocabTrainer.
You'll remember them forever.