In British English, a crammer is a school — often a small private one — that stuffs students with exam work in a short time. You go there not for a full education but to get through a test: school-leaving exams, university entrance, a professional paper. The feeling is speed and volume, not slow understanding. Older British speakers still use it; it can sound a little old-fashioned or slightly unkind, as if the place is packing heads rather than teaching. Americans almost never use this noun for a school; they are more likely to say a prep course or a test-prep school. (The word can also mean a person who crams overnight, but that is not this sense.) The -er here names the place that does the cramming, not a person.

補習班（英式；尤指趕考、惡補的學校）