Abarim Publications' online Biblical Hebrew Dictionary
פרע
Scholars identify three separate roots of the form פרע (para') but here at Abarim Publications we surmise that they're different faces of a single verb that means to confederate, to loosely bundle essentially free forces into a recognizable unity that in no way limits these forces.
פרע I
The verb פרע I (para' I) occurs a mere one time in the Bible, namely in Judges 5:2, where Deborah sings of "leaders who led" in Israel. Since in Deborah's time "there was no king in Israel; every man did what was right in his own eyes" (Judges 17:6, 21:25), these "leaders who led" were not formal or political leaders who coerced and ruled over Israel by force but rather freely acting people in Israel who were able to confederate decentralized tribes into a common purpose by proclaiming a convincing story.
This verb's sole derivative is the masculine noun פרע (pera'), which is commonly translated with "leader" but rather describes someone who arises organically from a population by his or her own merit and who is followed freely rather than by some sort of coercion or seduction. This phenomenon is so rare that our noun occurs beside Judges 5:2 only in Deuteronomy 32:42. It has no proper equivalent in English because this phenomenon does not occur in our modern world. In Deuteronomy 32:42 our word is used in a generous plural in the phrase ראש פרעות אויב (rosh para'ot 'oyob), which has evoked a broad array of translations: long-haired leaders of the enemy (NAS & JSP), heads of the enemy leaders (NIV & ASV), beginning of revenges upon the enemy (KJV), head of the princes of the enemy (Darby), head of the freemen of the enemy (Young).
פרע II
The verb פרע II (para' II) isn't used in the Bible but in cognate languages it may mean to sprout and describe the sprouting of progeny or of hair from a woman's head. This verb's sole derivative is the noun פרע (pera'), which refers to a certain hair style, namely that of free flowing hair or perhaps loosely bundled.
The word for hair is שער (se'ar), which is part of a group of words that also describes the cognitive quality of being familiar with something, and more specific to be afraid of something. In that same vein, our noun פרע (pera') describes long hair that is not or barely confined in a bundle or pony tail, and alludes to feelings or emotions that are aligned but not restricted in their development or expression. This noun occurs in Numbers 6:5 (a Nazirite shall let the locks of hair on his head grow long), and Ezekiel 44:20. It may also occur in Deuteronomy 32:42, which explains the translation of NAS and JSP. Likewise, Judges 5:2 may not speak of "leaders that lead" but "men [who] let grow their hair" (JSP) or even "freeing freemen" (Young).
פרע III
The verb פרע III (para' III) means to let go or leave be, and the sole reason why this verb is considered different from the previous two is that in the time modern Hebrew dictionaries were written the idea that a country could be governed on the principle of individual sovereignty was unthinkable. Nowadays we know better, and although free societies are rare or non-existent in our modern world, the hope that someday the members of our society may crown society's head like free flowing hair is alive and well. Our verb may describe the unbinding of a turban so that the hair is free to move (Leviticus 10:6). Priests were not permitted to unbind their hair, which meant that they were not permitted to let loose their emotions (Leviticus 21:10, see Isaiah 42:2), whereas lepers and interrogated women were obligated to unbind their hair, which means that they were free to cry their hearts out without restrictions or stifling decorum (Leviticus 13:45, see Proverbs 1:20).
Our verb may also be used in negative senses, namely to describe the getting out of control of children and immature adults who require government (Exodus 32:25, Proverbs 29:18, 2 Chronicles 28:19), the neglecting of proper counsel (Proverbs 1:25, 8:33) or discipline (13:18, 15:32). Our verb may be used to mean to distract (Exodus 5:4), to avoid (Proverbs 4:15) or to relent (Ezekiel 24:14).