1. geometric mean
等比中项
2. ethnicity
the fact that someone belongs to a particular ethnic group.
e.g. He said his ethnicity had not been important to him
3. curtail
If you curtail something, you reduce or limit it.
e.g. I told Louie that old age would curtail her activities in time.
4. polygraph
A polygraph test is a test which is used by the police to try to find out whether someone is telling truth.
e.g. Hill's lawyers announced she had taken and passed a polygraph test.
5. supersede
If someone is superseded by something newer, it is replaced because it has become old-fashioned or unacceptable.
e.g. Hand tools are relics of the past that have now been superseded by the machine.
6. canon
a canon of texts is a list of them that is accepted as genuine or important.
e.g. ' Wuthering Heights' is a central book in the canon of English literature.
