Some time ago, I posted about episodes of Justice League Unlimited that depicted Hawkgirl and several other DC characters as indirect counterparts to the Defenders. I found the animated version of Hawkgirl surprising, however, since the comic book character had changed her name to Hawkwoman by this point. In World's Finest #272 (Oct. 1981), she told Hawkman that she didn't like the connotation of the term girl and started correcting those who called her that by mistake. I prefer the way Hawkwoman sounds and wish her name had stayed that way.
Comic books have plenty of other examples of heroic peers with codenames that suggest different levels of maturity. The original X-Men notably included Marvel Girl and Iceman (the youngest member of the group). The Legion of Super-Heroes sidestepped the man/girl imbalance as both male and female heroes of the 30th century had youthful codenames. Superboy and the Legion of Super-Heroes #235 (Jan. 1978) revealed that people of the future used the terms boy and kid well into their twenties because scientific breakthroughs had vastly extended their life spans.