eldest /ˈɛldəst/ adjective Learner's definition of ELDEST
always used before a noun
: of the greatest age : oldest ◊ Eldest is usually used to describe people who are members of the same family.(家庭成员中)年龄最大的
the eldest
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used in comparing the ages of people who are members of the same family(家庭成员中)最年长的人