An Etymological Dictionary of the German Language/frei
frei, adj., ‘free, exempt, frank, voluntary,’ from the equiv. MidHG. vrî, OHG. frî; a common Teut. stem frija-, ‘free’ (unknown only to Scand.), which is assumed by Goth. freis (acc. sing., mas. frijana), AS. frî, freó (from frija-), E. free, OLG. frî. From these are formed the abstracts — Goth. freihals, ‘freedom,’ lit. ‘having one's neck free,’ AS. freóls, ‘freedom’ (also ‘peace, quiet’; comp. freólsdœg, ‘holiday’). Scand. frjáls for the non existent *frîr, ‘free,’ is identical with these words, being used as an adj. signifying ‘with a free neck’; akin to OHG. and MidHG. frîhals, ‘freeman.’ A ring around the neck was an OTeut. mark of a slave. Although frija- prevails throughout the Teut. group in its modern sense ‘free,’ to which W. ridd, ‘free’ (from prija-), also corresponds, yet there is some evidence that the meanings ‘dear, loved,’ once belonged to the adj. in earliest Teut.; comp. the corresponding abstr. Goth. frijaþwa, ‘love,’ AS. freód (for *frijôdus), ‘love, favour,’ AS. frîgu, ‘love’ (also freódryhten, freóbearn); allied to Goth. frijôn, ‘to love,’ mentioned under Freund and Friede. All these derivatives point to a Teut. root frî, ‘to cherish, spare, treat forbearingly’ (MidHG. vrî-ten, Goth. freidjan, ‘to spare’); frei in an active sense should perhaps be compared with held, which also denoted the relation of the higher to the meaner person. Frei is lit. ‘loving, loved, spared.’ This sense is placed beyond doubt by the earlier history of the word — Goth. frija-, from pre-Teut. priyó-; comp. Sans. priyâ-s, ‘dear, favourite,’ from the root prî ‘to rejoice, make well-disposed,’ In OAryan the fem. of the adj. priyã means ‘spouse,’ also ‘daughter’; to this OSax. frî, and AS. freó, ‘wife,’ correspond. With the Sans. root prî, OSlov. prijaja (prijati), ‘to assist,’ prijateljĭ, ‘friend,’ are also connected. See Freitag, freien, Freund, Friede, Friedhof.