The American Heritage® Dictionary of the English Language: Fourth Edition. 2000.
Appendix I
Indo-European Roots
ENTRY:
pr-
DEFINITION:
To love. Contracted from *pri- (becoming *priy- before vowels). Derivatives include filibuster, friend, and Friday. 1. Suffixed form *priy-o-.a.free, from Old English fro, free, and fron,freogan, to love, set free; b.filibuster, freebooter, from Dutch vrij, free. Both a and b from Germanic *frijaz, beloved, belonging to the loved ones, not in bondage, free, and *frijn, to love. 2. Suffixed (participial) form *priy-ont-, loving. friend, from Old English frond,frond, friend, from Germanic *frijand-, lover, friend. 3. Suffixed shortened form *pri-tu-.a.Siegfried, from Old High German fridu, peace; b.affray, afraid, from Old French esfreer, to disturb, from Vulgar Latin *exfredre, to break the peace, from ex-, out, away (see eghs) + *fridre, to make peace, from Germanic *frithu-, peace; c. Germanic *frij-, peace, safety, in compound *berg-frij- (see bhergh-2). ac all from Germanic *frithuz, peace. 4. Suffixed feminine form *priy--, beloved. a.Frigg, from Old Norse Frigg, goddess of the heavens, wife of Odin; b.Friday, from Old English Frgedæg, Friday, from Germanic compound *frije-dagaz, day of Frigg (translation of Latin Veneris dis, Venus's day). Both a and b from Germanic *frijj, beloved, wife. (Pokorny pri- 844.)