adj.
Being in compliance with the law; lawful: a legitimate business.
Being in accordance with established or accepted patterns and standards: legitimate advertising practices.
Based on logical reasoning; reasonable: a legitimate solution to the problem.
Authentic; genuine: a legitimate complaint.
Born of legally married parents: legitimate issue.
Of, relating to, or ruling by hereditary right: a legitimate monarch.
Of or relating to drama of high professional quality that excludes burlesque, vaudeville, and some forms of musical comedy: the legitimate theater.
tr.v., -mat·ed, -mat·ing, -mates. (-māt')
To make legitimate, as:

To give legal force or status to; make lawful.
To establish (a child born out of wedlock) as legitimate by legal means.
To sanction formally or officially; authorize.
To demonstrate or declare to be justified.

[Middle English legitimat, born in wedlock, from Medieval Latin lēgitimātus, law-worthy, past participle of lēgitimāre, to make lawful, from Latin lēgitimus, legitimate, from lēx, lēg-, law.]

Law Encyclopedia: Legitimate

To make lawful, such as when a child is born prior to the parents' marriage and they subsequently wed and thereby confer upon the child the same legal status as those born in lawful wedlock.

That which is lawful, legal, recognized by law, or in accordance with law, such as legitimate children or legitimate authority; real, valid, or genuine.

Word Tutor: legitimate

Having the sanction of law or established custom.

To cherish what remains of the Earth and to foster its renewal is our only legitimate hope of survival. — Wendell Berry