shirt-sleeve

Or shirt·sleeve,

[shurt-sleev]

adjective

1. not wearing a jacket; informally dressed.

   a shirt-sleeve mob.

2. warm enough to live or work in without wearing a jacket or coat.

   shirt-sleeve weather in November.

3. simple, plain, and informal; direct and straightforward in approach, manner, etc..

   shirt-sleeve diplomacy.

Word History and Origins

Origin of shirt-sleeve¹

First recorded in 1560–70