Many of my students ask, “What is the difference between the expressions, girl, lady, and woman?”
This is not a simple question, but I have checked with dictionaries as well as many native speakers. Let me give you a summary of my research.
As a rule of thumb, use “girl” for any female up to college age, use “young woman” until about age 30, and use “woman” after 30. The word “young” can be added depending on the age of the speaker. The word “old” is not really appropriate; instead, give the female person’s age if it is relevant to the story you are telling. Sometimes the distinction between “girl” and “young woman” depends more on perceived maturity and less on actual age.
For feminists—especially many native English speakers who lived through the 1960s and 1970s women’s movement, the term “woman” is preferred in everyday speech over “lady” to designate an adult female for two reasons.
First, “woman” is the linguistic counterpart to “man.” Second is the perception that the word “lady” has classist and sexist connotations; to them, a “lady” represents an inconsequential female of no personal accomplishment (other than perhaps connection to British nobility, think: Lords and Ladies). The modern assumption is that any female who can compete head to head with a man should have the parallel expression of “woman.”
Older Americans of both genders who do not identify with the women’s movement or notions of legal/financial/political equity tend to use the term “lady.” This includes expressions which “mark” (and therefore diminish) the position of female professionals: lady doctor, lady mechanic, lady pilot, lady engineer. This group may also include speakers of lower education or more rural status who identify female office workers as the “office girls” (even though they would never say “office boys” to identify the males who work in the office).
One exception: In a public place, if a female is unknown to you, it may feel more polite to refer to a stranger as “lady.” For example: the lady who dropped her purse or: This lady was ahead of me in line (so please wait on her next).
Here is a quiz you can take to test yourself...and don’t forget to share it with the other females in your life.
Choose girls, ladies, or women for the sentences below.
1. We encouraged as many ______________ and boys as possible to audition for the play.
2. Good afternoon, ______________ and gentlemen. Thank you for inviting me to speak here today.
3. Two ______________ just joined us on the senior advisory board this past week.
4. I met three young ______________ in their 20s with a really interesting new product.
5. In 2015, there were 20 ______________ serving in the U.S. Senate.
6. Kids, if you can’t act like ______________ and gentlemen, I’m going to cancel Friday’s special trip.
7. Over 50% of the medical students at the university today are ______________.
8. Do you know those two ______________ talking to the President?
9. Penny told Amy they were having a ______________ night out.
10. How many members of the President's Cabinet members are ______________?
For a longer list of examples, including many nuances, go here.