Definition of scotch mist:
(n) :
(UK) A cold and penetrating mist, verging on rain.
(n) :
A drink of Scotch whisky served with ice and lemon peel.
(n) :
(UK, dialect, chiefly Lancashire and Yorkshire, idiomatic) Something that is hard to find or does not exist.
(n) :
(World War II) Something imaginary, nonexistent, or overlooked.
(n) :
The perennial flowering plant Galium sylvaticum.