Pipefuls
The plural form of plastic is plastics.
The plural form of building is buildings.
The plural form for the noun 'material' is materials.
The plural form is technologies.
The plural form of system is systems.
The word "trachea", the term used for the wind-pipe, is in the singular. The plural is "tracheas" or, infrequently, "tracheae", both of which are recognized by the dictionary.
The plural form of him, her, or it is them. (objective pronouns)
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 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.
"Important" is an adjective. It does not have a plural form.