The word 'mucous' is an adjective, it has no plural form.
The noun 'mucus' is an uncountable (mass) noun as a word for a substance.
The word beads is a plural noun. The singular is bead.
The word whims is a plural noun. The singular is whim.
The word kindergarten is a singular noun. The plural form is kindergartens.
The word apple is a singular noun. The plural would be apples.
The word tree is a singular noun. The plural would be trees.
The word team is singular; the plural form is teams.
These is plural, this is singular
Lance is singular. Lances is plural.
The word 'Phenomenon' is singular. The plural form is 'Phenomena'.
The word metastasis is singular, metastases is plural.
The word "ground" can be both singular and plural. Singular: "The ground is wet." Plural: "The grounds of the park are well-maintained."
Louse is singular. The plural form is lice.
No, the word "list" is singular. The plural form of "list" is "lists."
It's singular. The plural is cafeterias.
Verbs cannot be singular or plural. Has is after singular nouns.
Tool is singular. Tools is plural.
Caveman is singular. Cavemen is plural.