Source : Webster's Revised Unabridged Dictionary (1913)

Lawful \Law"ful\, a.
   1. Conformable to law; allowed by law; legitimate; competent.

   2. Constituted or authorized by law; rightful; as, the lawful
      owner of lands.

   {Lawful age}, the age when the law recognizes one's right of
      independent action; majority; -- generally the age of
      twenty-one years.

Source : WordNet®

lawful
     adj 1: conformable to or allowed by law; "lawful methods of
            dissent" [ant: {unlawful}]
     2: according to custom or rule or natural law [syn: {orderly},
        {rule-governed}]
     3: having a legally established claim; "the legitimate heir";
        "the true and lawful king" [syn: {true(a)}, {rightful(a)}]
     4: authorized, sanctioned by, or in accordance with law; "a
        legitimate government" [syn: {legitimate}, {licit}]