When cloth is Sanforized, a factory has already made it shrink on purpose, under control, before it is cut into a shirt or trousers. After that, washing should not make the clothes much smaller. The name comes from Sanford Lockwood Cluett, who invented the method; it is a trademark, so you will often see a capital S on a clothing label. Everyday English might just say pre-shrunk. Though actually, no treatment makes shrinking impossible for ever — it greatly reduces it, especially in cotton. And it is not the same as sanitized: that word is about germs and cleanliness, not about size.

預縮、防縮（商標名；衣服標籤上常見）