from
The Collaborative International Dictionary of English v.0.48
Congou \Con"gou\, Congo \Con"go\, n. [Chin. kung-foo labor.]
Black tea, of higher grade (finer leaf and less dusty) than
the present bohea. Also called {English breakfast tea}. See
{Tea}.
[1913 Webster +PJC]
Of black teas, the great mass is called Congou, or the
"well worked", a name which took the place of the Bohea
of 150 years ago, and is now itself giving way to the
term "English breakfast tea." --S. W.
Williams.
[1913 Webster]