No, it is not. It is a noun meaning an abundance, or overabundance (excessive in number).
Plethora is singular and the plural form is plethoras
There was a plethora of food on the table at Thanksgiving.
Plethora is a noun.
The noun plethora (a plethora) uses singular verb forms.The word plethora is an uncountable (mass) noun, a type of aggregate noun that refers to an unspecified but large number of elements, e.g. a plethora of choices.
Plethora is singular and the plural form is plethoras.
well that word is a adjective, so it depends.....
It is neither an adjective nor an adverb. "Plethora" is a noun. Use it like you might use the nouns "abundance" "quantity" or "excess", when what you want to convey is "huge amount" or "overabundance". I don't think it is often pluralized; have never seen that, anyway. Also rare would be its adjective form "plethoric", leading to a stretch to make the adverb "plethorically". Good for "plethora" for being one of those words that has very very few relatives in the language!
"Plethora" is a singular noun, so you say "is a plethora."
Superabundant, overstock, plethora, oversupply (when surplus is a noun) Excess, superfluent, leftover (when surplus is an adjective)
Plethora is singular and the plural form is plethoras
(Plethora means an abundant excess as a bountiful excesss such as riches.)"The Thanksgiving feast was a plethora of favorite foods of the family.""There was a plethora of costumes to choose from for the masquerade.""From the plethora of possible names for the project, he chose the most apt."
"Is", since plethora is in singular form
There was a plethora of food on the table at Thanksgiving.
Plethora is a noun.
The noun plethora (a plethora) uses singular verb forms.The word plethora is an uncountable (mass) noun, a type of aggregate noun that refers to an unspecified but large number of elements, e.g. a plethora of choices.
Plethora is singular and the plural form is plethoras.
The plethora of escapes from supposedly secure prisons embarrassed the hapless wardens. The success of his videos inspired a plethora of imitators.