1shirt·sleeve 
/ˈʃɚtˌsli:v/ noun
plural shirt·sleeves /ˈʃɚtˌsli:v/ noun [count] : the sleeve of a shirt
in (your) shirtsleeves
: wearing a shirt but no coat or jacket
▪ a man in his shirtsleeves ▪ It was hot and most of the crowd was in shirtsleeves.
▪ a man in his shirtsleeves ▪ It was hot and most of the crowd was in shirtsleeves.
