un·prin·ci·pled /ˌʌnˈprɪn(t)s(ə)pəld, səbəld/
  (a.)無原則的,不道德的,不合人道的
  Un·prin·ci·pled a.  Being without principles; especially, being without right moral principles; also, characterized by absence of principle. -- Un*prin*ci*pled*ness, n.
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  unprincipled
       adj 1: lacking principles or moral scruples; "freedom from coarse
              unprincipled calumny"- A.E.Stevenson [ant: principled]
       2: having little or no integrity