Looking on the internet deeply has found these results:

winter break is the most popular phrase on the web.

mid-term holiday 12,530 results on the web	winter break 116,400,000 results on the web More popular!
Some examples and use cases from the internet:	Some examples and use cases from the internet:
Mid Monday 15 February 2016; Tuesday 16 & Wednesday 17 February In Jan 7, 2016 ... Mid Service training school �... Term Starts term holiday, aims to separate the two semesters. It takes place for two weeks between late December and early January, coinciding with Christmas and �... Wednesday 6 January 2016; Mid Term Holiday 6 days ago ... 2015/2016 Academic Year. Term, Term Begins, Mid Term Holiday, Term Ends, Days. Begins, Ends. Autumn 2015, Tuesday 1st September�...	It doesn't look like this phrase is very popular! The search could not find any examples on the internet.

mid-term holiday

12,530 results on the web

winter break

116,400,000 results on the web

More popular!

Mid
Monday 15 February 2016; Tuesday 16 & Wednesday 17 February In
Jan 7, 2016 ... Mid
Service training school �...
Term Starts
term holiday, aims to separate the two semesters. It takes place for two weeks between late December and early January, coinciding with Christmas and �...
Wednesday 6 January 2016; Mid Term Holiday
6 days ago ... 2015/2016 Academic Year. Term, Term Begins, Mid Term Holiday, Term Ends, Days. Begins, Ends. Autumn 2015, Tuesday 1st September�...

It doesn't look like this phrase is very popular! The search could not find any examples on the internet.