"set apart and consecrated to a deity or to a sacred purpose by a solemn act or by religious ceremonies; devoted with earnest purpose, as to some person or end," c. 1600, usually of things, writings, property, etc., past-participle adjective from dedicate (v.).
Of persons, "devoted to one's aims or vocation," attested clearly by 1936, but the sense shift can be felt in Lincoln's Gettysburg Address, which opens talking of "a new nation, conceived in Liberty, and dedicated to the proposition that all men are created equal," and a few lines later reintroduces the word personally: "It is for us, the living, rather, to be dedicated here to the unfinished work which they who fought here, have, thus far, so nobly advanced. It is rather for us to be here dedicated to the great task remaining before us ...."
Of things, "made to be available only for a particular purpose or class of user," by 1969. Related: Dedicatedly.