Free (a.) - Free Beer!
Without hindrance, obstruction, restriction, or regulation.
Also given without cost or gratis.
History & Etymology
The word that eventually became free in English had a very different meaning all the way back in Proto-Indo-European. The word priy-a- meant “one’s own or beloved” and it’s root pri- meant “to love”.
I was especially struck by the almost contradictory meaning of “one’s own” that seems to imply ownership, which is often considered the opposite of free.
Free is another great example of sounds changing in words. For example when Priya move in to Sanskrit as priyā it kept the “p” sound at the beginning. When it moved in to Proto-Germanic the sound “p” sound at the beginning of the word, morphed from a bilabial stop, a sound made by closing your lips together the releasing the air behind them, to the labiodental fricative sound “f” which is made by partially blocking the air flow by putting your lower lip up to your teeth. This is how we got from the word priya to the Proto-Germanic word frija.
Around the same time as this sound change the word began being used in another since. It still meant “dear or beloved” but it also began being used to mean “not in bondage”. This meaning is much closer to the way we use the word today. This transformation in meaning seems to have come about because the free people in a clan or family were related by blood, or to go back to PIE definition “one’s own” blood, or “beloved” family members. This would be opposed to slaves or servants who weren’t related by blood or kinship.
When free entered Old English as freo it already had the meaning of “not in servitude to another” and had lost most of its meaning of “beloved”. Though in some cases it was used to describe people of Noble Birth.
Other derivatives of from the same origin made it into English. Such as...
Friday is named after the Norse goddess Frigg whose name means “beloved”.
Friend comes from the Old English freod and Proto-Germanic frijand.
How the word free came to mean “without charge or gratis” in English is another story. I’ve found dates that put this usage originating around 1580 and even as early as 1200, but none of the sources really did a great job of explaining how it acquired that meaning. Through a bunch of logic leaps, and searching for terms like gratis and free I was reminded of the phrase, “He got off scot-free”. I looked up scot-free in the Oxford English dictionary, and one look at the etymology and it all clicked in my brain.
Etymology: Apparently an alteration of shot-free adj.
Shot, that was the connection. That took me back to when I read Mark Twain’s Connecticut Yankee in King Arthur's Court, at one point in the story Mark Twain attempts to create a fictional etymology for the English phrase “paying the shot”. The main character creates a currency where you carry small round pellets in a container on your belt and you can dispense them easily to make change or pay for goods, and because these pellets looked like buckshot or birdshot used in a shotgun he called them “shots”. This was all made up of course, the phrase didn’t come from a time traveling American, but the shot in shot-free meant the portion someone had to pay for collective entertainment at a bar or tavern. Kind of like a cover charge today. To get off scot-free or shot-free was to leave without paying your share of the cost. Over time you can imagine bar owners advertising shot-free entertainment and over time the shot might get dropped from the beginning leaving just free entertainment.
That seems to be why in English free has two different meanings. It’s the difference between free speech and free beer.