This is the 9881st most frequent Japanese word.
試着
"試着" means "trying on clothes."
Here, '試着' is used as a noun to denote the act of trying on clothes, and the sentence asks for permission to perform this action.
このドレスを試着してもいいですか？
May I try on this dress?
In this sentence, '試着' is part of the compound noun '試着室' (fitting room), indicating the location where clothes are tried on.
試着室はどこにありますか？
Where is the fitting room?
Here, '試着' is used as a verb phrase '試着してみました', describing the action of trying on new clothes as part of past experiences.