The plural of thesaurus is thesauri or thesauruses.
A thesaurus is a reference book or online resource that provides synonyms, antonyms, and related words for a given term or concept. It helps writers, students, and language enthusiasts expand their vocabulary and find alternative expressions to enhance their communication and writing skills.
Singular:
Plural:
The graph shows the occurances of the plural of thesaurus in written English since 1800 using Google's Ngram Viewer.
Sources: