Singular form for old-fashioned

Answer 1

The adjective "old-fashioned" does not take singular or plural because it is an adjective. Only nouns (or other words acting as nouns) can be singular or plural.

For example: Old-fashioned lady is one lady who's old-fashioned; old-fashioned ladies can be 2 or more ladies who are old-fashioned. In both cases, the adjective is the same; only the noun changes according to number.

Answer 2

Old-fashioned (singular)