The word "tomboy" is a compound word which combines "tom" with "boy". Though this word is now used to refer to "boy-like girls", the etymology suggests the meaning of tomboy has changed drastically over time. 
In 1533, according to the Oxford Dictionary of English, "tomboy" was used to mean a "rude, boisterous or forward boy". By the 1570s, however, "tomboy” had taken on the meaning of a "bold or immodest woman", finally, in the late 1590s and early 1600s, the term morphed into its current meaning: "a girl who behaves like a spirited or boisterous boy; a wild romping girl." 
https://en.wikipedia.org/wiki/Tomboy

There you have it: Tomboys, challenging gender stereotypes since 1600. And looking damn good at the same time. All the more outrageous that Flux seems to have no idea what a tomboy is. But this changes now with this lora (hopefully).