street clothes; outdoor clothes; clothes for going out
Refers to clothing worn outside the home, as opposed to indoor wear or loungewear. Often used in contrast with 部屋着 (indoor clothes).
I change from indoor clothes to outdoor clothes.
With an unexpected visitor, I hurriedly put on my street clothes.
外出着 refers to clothes worn when going out, the opposite of 寝間着, which is worn only at home for sleeping.
Compound of 外出 (going out) and 着 (clothing).