1 an expert in a particular subject who is asked by a court of law or other official group to give advice （法院等请来就某问题发表意见的）技术顾问

2 a person who calculates the value or cost of sth or the amount of money to be paid 估价人；估算员: an insurance/a tax assessor 保险损失评估员；估税员

3 a person who judges how well sb has done in an exam, a competition, etc （考试、比赛等的）评判员: Marks are awarded by an external assessor. 由外面的评判员来打分。