What is the singular possessive form of dress?

There are two accepted forms for possessive singular nouns ending in s:

Add an apostrophe (') after the existing s at the end of the Word: dress'

Add an apostrophe s ('s) after the existing s at the end of the Word: dress's

Examples:

I like this dress' color.

I like this dress's color.

Note: If you are a student, use the form that is preferred by your teacher.