门
mén
I n.
1) door; gate; doorway; gateway; opening
2) Surname
3) bio. phylum
II b.f.
1) valve; switch (阀门, 电门)
2) way to do sth.; knack (门路)
3) family; house
王门李氏 Mrs. Wang, née Li
4) class; category
5) (religious) sect; school (of thought) (佛门)
III m.
for courses, branches of science, canons, etc.