"Clyde Gill" wrote:

Half-Bottle
375 milliliters or one half of the standard bottle size. Also known as
a
"split" or a "tenth".

I think a split is 187 mls.

The term is used for both the 187 ml bottle and the 375 ml bottle (as you
can verify with an internet search for "split wine bottle"). It originally
applied to the 375 ml bottle, and derived from "Let's split a bottle".

The 187 ml bottle is a relatively new creation.