The singular form of the plural noun smiths is smith.
The singular possessive form is smith's.
example: I bought this at a goldsmith's shop on Main Street.
pilot's
enemy's
Actress'
The singular possessive form of city is city's
The singular possessive noun for child is child's.
Buses' is plural possesive.
Dad? Although father is already singular "My father's car" singular possesive
The singular possessive of "Bob" is "Bob's."
tooth's - as in "A tooth's root extends down into the jawbone."
Calf's. The calf's tail was swatting at the fly.
Singular: hypothesis Plural: hypotheses
Absract, Compound, Collective, Proper, Singular, Plural, Concrete, Possesive