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Webster 1913 Edition

(ĕth′ĭ-sĭst)

Noun.

One who is versed in ethics, or has written on ethics.

ethicist ‎(plural ethicists)

A person, especially a philosopher, who studies ethics (principles governing right and wrong conduct).
A person who advocates a particular set of principles governing right and wrong conduct.

person who studies principles governing right and wrong conduct