shirt sleeves

Short definition from Wiktionary

Noun

1. 1
   plural of shirt sleeve
2. 2
   Preceded by in: wearing only a shirt without a coat, jacket, or comparable protective covering over it.
3. 3
   A working-class socioeconomic status (not requiring a professional business jacket).
4. 4
   plural of shirt-sleeve
5. 5
   Alternative form of shirt sleeves.