Originally coined as a term to describe mercenary soldiers, the phrase "free lance" has come a long way in the past 200 years. Sir Walter Scott, originator of the term, first wrote it in the book Ivanhoe in 1820:
I offered Richard the service of my Free Lances, and he refused them — I will lead them to Hull, seize on shipping, and embark for Flanders; thanks to the bustling times, a man of action will always find employment.
In its first usage, Scott used the phrase as a proper noun, literally naming his soldiers for hire "Free Lances". A "free lance" very quickly became used synonymously with "mercenary," and while the meaning stuck for a good 40 years, by the 1860s the usage became purely figurative. By the end of the 19th century a freelance was a person who "acts independently without being affiliated with, or authorized by, an organization." No longer about medieval mercenary soldiers, "freelance" evolved to carry a meaning that hinted at intrigue and excitement.
At the turn of the 20th century, freelance was officially recognized as a verb by the Oxford English Dictionary. "Freelancing," as defined by Oxford, is "earn[ing] one's living as a freelance". While still evoking images of espionage and danger, it wasn't until more modern times that "freelance" took on a more mundane meaning.
Used more recently as an adjective, the phrase "free lance" seems to only conjure up images of writers, programmers, and artists with serious caffeine addictions and thick-rimmed glasses. Though no longer hardened mercenaries, freelancers are still individuals who earn a living by acting independently without authorization from any organization, and as Sir Walter Scott said, "a man of action will always find employment."