An old post on the topic of referring to college-age or older female people as girls vs. women got a lot of comments back in 2006, and the topic still pops up now and again in comments and conversation. As far as I can tell, these days, girl is the more common term used to denote young(ish) female persons.
Certainly the term girl is also used by some older women, some of whom are related to me, who tend to refer to groups of other older women as girls, but my topic today is the relative use of girls vs. women to refer to young(ish) female persons.
It took me awhile to get used to the term girls when applied to young female adults, and I still tend to use the term women, but I suppose that just shows my age. As long as girls is used in parallel with boys/guys, rather than with "men", however, I no longer think it is offensive to refer to young women as girls, especially if it is used by other young people to refer to themselves and their peers.
I admit that with some reluctance, so I guess I can't say that I am really used to it, even now, because I still find it a bit startling to hear someone in their 20's-30's, or even older, referred to as a girl. The sheer number of adults who don't consider it demeaning to be referred to as a girl, however, suggests that the term has no particular negative connotation about capability or maturity.
At the same time, I think it is too bad if woman is viewed as a technical, formal, stodgy, and perhaps even offensive term. Female children are girls, and at some point when these children become adults, they are women, just as boys become men. When I was 5 years old or 9 years old, I was a girl. I couldn't imagine wanting to use the same term for myself when I was 30.
Nevertheless, girl is a pervasive term these days. For those of us who feel disappointed by this trend, perhaps we can come to an understanding with those who do not share our disappointment: those who prefer the term women can try to realize that girl is not necessarily an offensive way to refer to an adult female (except in the circumstance in which males are men and females of the same age are girls), and those who prefer the term girl can try to realize that woman is not an offensive or inappropriate way to refer to an adult female.
7 years ago