Ever since Mega Man X first broke onto the Super NES scene, the term "Maverick" has been a longstanding part of the series' jargon. We know it as the localized form of the term "Irregular" from Japan, which has pervaded games in other Rockman series from Zero to ZX and even Legends. Sometimes it's even used among fans in fun, though it has also been used somewhat inappropriately at times. But where did the term come from? That's something not too many people likely ask. Luckily, for those who never bothered but are curious just the same, The New York Times provides an answer. Generally speaking, The Mega Man Network is not the place for political discussion, and that does not change here. However, there is little arguing that the term "Maverick" has been used to describe Presidential candidate Senator John McCain, and this article goes into detail about the origin of the term-- and what the family from whom it came thinks of McCain's use as well. But again, that's not to be discussed here.
Those whose initial exposure to the term was through Sigma's armies may find one part in particular ironic:
In the 1800s, Samuel Augustus Maverick went to Texas and became known for not branding his cattle. He was more interested in keeping track of the land he owned than the livestock on it, Ms. Maverick said; unbranded cattle, then, were called “Maverick’s.” The name came to mean anyone who didn’t bear another’s brand.
Still don't get the irony?
Sigma's followers all bear his symbol, or his "brand" if you will, along with others dubbed as Mavericks in the X series. Even more ironic is that it took until Maverick Hunter X before the Hunters even had a symbol of their own.