As in every other discipline, such as math or science, proper terminology is important so that explanations related to Wing Chun are clear and concise. Chinese terminology is sometimes useful, because it offers a shorter way to describe things. There is no need to get carried away however, by referring to everything in Chinese. Thus, a punch should be called a punch.
The following terminology uses the most common spelling which has appeared in the literature.
Note: a thrusting hand, or poking hand, or pointing hand, or just a poke is called Bil sau. In Cantonese, the term sounds more like "Biu sau"; therefore you will sometimes see this spelling. For the non-Chinese, it is easier to pronounce Bil sau, so we prefer the latter spelling.
We recommend using the simplest spellings. Therefore, use Tan sau, rather than Taun sau or Tahn sau.
TIP: use Pak Sau, Lap Sau and Huen Sau to deal with obstructions
Techniques can now be described as follows: Person A throws a punch. B uses an outside poke or outside Bil sau to defend.
The Wing Chun Kung Fu Digital Library