The noun 'thesaurus' is singular (one thesaurus).
The plural forms are thesauruses and thesauri, both are accepted spellings.
The plural forms thesauruses and thesauri are both acceptable forms of the word thesaurus.
theasauri or theasauruses
practitioner is singular (plural practitioners)sofa is singular (plural sofas)satellite is singular (plural satellites)clips is plural (singular clip)dentist is singular (plural dentists)dollars is plural (singular dollar)article is singular (plural articles)magazines is plural (singular magazine)laminator is singular (laminators is plural)radios is plural (singular radio)
Thesauri (or thesauruses) is the plural form of thesaurus.
singular and plural
Singular: book / Plural: books Singular: cat / Plural: cats Singular: child / Plural: children Singular: foot / Plural: feet
Are is plural. "Is" is singular. For example, "There is a glove on the chair". That is singular. "There are gloves on the chair". That is plural.
"Has" is singular, e.g. He has, she has. "Have" is plural, e.g. They have, we have. The exception is "I" - e.g. I have.
Thesauri or thesauruses is the plural of thesaurus. Both are acceptable
The word team is singular; the plural form is teams.
diagnosis is singular diagnoses is plural sis = singular ses = plural
"Notebook" is singular. The plural form is "notebooks."