The word 'broad' is an adjective. Adjectives don't have plural forms, adjectives have degrees:
The plural form for the noun arch is arches.
The noun 'fungi' is the plural form of the noun 'fungus'.
The plural form of the noun defendant is defendants.The plural possessive form is defendants'.Example: All of the defendants' lawyers have spoken to their clients.
The plural form of itch is itches.
The plural form of inadvertence is inadvertences.
The word 'broad' is an adjective. Adjectives don't have plural forms, adjectives have degrees:broad (positive)broader (comparative)broadest (superlative)
The noun spectacles is a shortened form for the term 'pair of spectacles'. The plural form is two pairs of spectacles.The nouns spectacles belongs to a group of nouns that are a shortened form for 'a pair of', for example:binocularsglassespantsscissorsshearsshortsspectaclestongstrouserstweezersAll of these nouns are made plural by changing 'a pair of...' to 'pairs of...'.
Bridges is the plural form of bridge.
"Beliefs" does not have a plural form, as it is already plural. Beliefs is the plural form of belief.
There is no plural form for the word, countries. This word itself is a plural.
"Groceries" is the plural form of "grocery."
The plural form of "meter" is "meters."
The plural form of the demonstrative pronoun 'that' is those.
The noun form of the adjective 'broad' is broadness.The verb form of the adjective 'broad' is to broaden.
The plural form for the noun sergeant is sergeants; the plural possessive form is sergeants'.
It has no plural form.
The plural form of rung is rungs.