learning to read chinese to study go

[John Fairbairn]

The important usage is as momentum. Newton's balls. You play a move that induces a reply from the opponent which in turn makes you play on a point you were going to have to play anyway. You have, in other words, inserted a forcing exchange in your favour before submitting to being forced yourself.

It's usually been seen in Japan as the mark of a 5-dan player. The Chinese usage is borrowed from Japan.

The choice of "momentum" as a translation is not fixed in English, but as the definition of choushi is "ishi no hazumi", which means "a groups's momentum", it probably should be.

The word has other uses even in go. One common one is to say a player is in good form.