* Nakedness: This is the most direct opposite, meaning being without any clothing.
* Bareness: This is similar to nakedness but can also refer to something being exposed or uncovered.
* Unclothed: This is a more formal way of saying naked.
* Disrobe: This is a verb meaning to remove clothing.
You could also use more specific antonyms depending on the context. For example, if you were talking about formal apparel, the antonym could be casual clothes.
Ultimately, the best antonym for "apparel" depends on the specific situation and what you want to emphasize.