员
yuán
(bound form) person engaged in a certain field of activity
(bound form) member; classifier for military generals
mouth (口) + shell/value (贝) = a person with a counted role
贝, the cowrie shell, was an ancient unit of value and counting — it grounds the idea of a numbered member or post. 口 may suggest a voice or presence in the group, though its role here is partly structural.
Words with 员
临时演员
lín shí yǎn yuán
an extra (in a movie)
通讯员
tōng xùn yuán
correspondent
速记员
sù jì yuán
stenographer
运动员
yùn dòng yuán
athlete
运货员
yùn huò yuán
porter
选举委员会
xuǎn jǔ wěi yuán huì
Election Committee (Hong Kong)
邮递员
yóu dì yuán
mailman
配速员
pèi sù yuán
(sports) pacemaker; pacesetter (in long-distance running)
配镜人员
pèi jìng rén yuán
optician
医务人员
yī wù rén yuán
medical personnel
医护人员
yī hù rén yuán
medical personnel
自动柜员机
zì dòng guì yuán jī
automated teller machine (ATM)