Old English freodom "power of self-determination, state of free will; emancipation from slavery, deliverance;" see free (adj.) + -dom. Meaning "exemption from arbitrary or despotic control, civil liberty" is from late 14c. Meaning "possession of particular privileges" is from 1570s. Similar formation in Old Frisian fridom, Dutch vrijdom, Middle Low German vridom.

It has been said by some physicians, that life is a forced state. The same may be said of freedom. It requires efforts, it presupposes mental and moral qualities of a high order to be generally diffused in the society where it exists. [John C. Calhoun, speech, U.S. House of Representatives, Jan. 31, 1816]

[F]reedom is only truly freedom when it appears against the background of an artificial limitation. [T.S. Eliot, "Reflections on 'Vers Libre'"]

Freedom fighter attested by 1903 (originally with reference to Cuba). Freedom-loving (adj.) is from 1841.  Freedom-rider is recorded from 1961 in reference to civil rights activists in U.S. trying to integrate bus lines. 

prī-, Proto-Indo-European root meaning "to love." In some languages (notably Germanic and Celtic) it developed derivatives with the sense "free, not in bondage," perhaps via "beloved" or "friend" being applied to the free members of one's clan (as opposed to slaves).

It forms all or part of: afraid; affray; filibuster; Frederick; free; freebooter; freedom; friend; Friday; Frigg; Godfrey; Geoffrey; Siegfried; Winfred.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit priyah "own, dear, beloved," priyate "loves;" Old Church Slavonic prijati "to help," prijatelji "friend;" Welsh rhydd "free;" Old English freo "exempt from; not in bondage, acting of one's own will," Gothic frijon "to love," Old English freod "affection, friendship, peace," friga "love," friðu "peace," Old Norse Frigg, name of the wife of Odin, literally "beloved" or "loving."

1590s, "straightness;" 1610s, "freedom from ambiguity;" see direct (adj.) + -ness. 

c. 1200, purite, "freedom from moral contamination, sinlessness, innocence; righteousness; chastity," from Old French purete "simple truth," earlier purte (12c., Modern French pureté), from Late Latin puritatem (nominative puritas) "cleanness, pureness," from Latin purus "clean, pure, unmixed; chaste, undefiled" (see pure (adj.)). From mid-15c. as "freedom from admixture or adulteration."