Legitimate, a.
Etymology: [LL. legitimatus, p. p. of legitimare to legitimate, fr. L. legitimus legitimate. See Legal.]
1. Accordant with law or with established legal forms and requirements; lawful; as, legitimate government; legitimate rights; the legitimate succession to the throne; a legitimate proceeding of an officer; a legitimate heir.
2. Lawfully begotten; born in wedlock.
3. Authorized; real; genuine; not false, counterfeit, or spurious; as, legitimate poems of Chaucer; legitimate inscriptions.
4. Conforming to known principles, or accepted rules; as, legitimate reasoning; a legitimate standard, or method; a legitimate combination of colors. Tillotson still keeps his place as a legitimate English classic. Macaulay.
1 more senses
5. Following by logical sequence; reasonable; as, a legitimate result; a legitimate inference.
1 other Webster entry under this spelling
Legitimate, v. t. [imp. & p. p. Legitimated; p. pr. & vb. n. Legitimating.]
To make legitimate, lawful, or valid; esp., to put in the position or state of a legitimate person before the law, by legal means; as, to legitimate a bastard child. To enact a statute of that which he dares not seem to approve, even to legitimate vice. Milton.
Shades of meaning
Fernald has no entry of its own for legitimate; he lists it under authentic.
Where he writes about it:
We speak of accepted conclusions, certain evidence, current money, genuine letters, a legitimate conclusion or legitimate authority, original manuscripts, real value, received interpretation, sure proof, a true statement, a trustworthy witness, a veritable discovery. — from authentic