The Collaborative International Dictionary of English v.0.48:

Ethic \Eth"ic\, Ethical \Eth"ic*al\, a. [L. ethicus, Gr. ?, fr.
   ? custom, usage, character, dwelling; akin to ? custom, Goth.
   sidus, G. sitte, Skr. svadh?, prob. orig., one's own doing;
   sva self + dh? to set: cf. F. ['e]thique. See So, Do.]
   Of, or belonging to, morals; treating of the moral feelings
   or duties; containing percepts of morality; moral; as, ethic
   discourses or epistles; an ethical system; ethical
   philosophy.
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         The ethical meaning of the miracles.     --Trench.
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   Ethical dative (Gram.), a use of the dative of a pronoun to
      signify that the person or thing spoken of is regarded
      with interest by some one; as, Quid mihi Celsus agit? How
      does my friend Celsus do?
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