old girl 
noun
1British A former female student of a school or college: one of the college’s most famous old girls...
- Famous old girls include Harriet Harman, constitutional affairs minister, and Rosalind Franklin, the DNA pioneer.
- Famous old girls and boys include actress Diana Rigg, Prime Minister Herbert Asquith and factory reformer Richard Oastler.
- The former pupil, whose daughter is now a pupil at the school, tracked down old girls from the intervening years via internet websites.
1.1A former female member of a sports team or company: other old girls of this magazine have done well...
- The old girl, I must say, has been a hardy sort, as she has had to be to come through what she has, but the passing of the years has not been flattering to her.
- Thankfully the old girl fell away from the buildings.
- The past and present combine in the first act, during which overweight Stella and the old girls get together again in trying to remember a routine, which leaves them winded.
2 informal, chiefly British An elderly woman: they’re a couple of harmless old girls...
- My source told me of the time that he went to a retirement village with Kelly, and Kelly ended up playing the piano for the old girls in residence.
- The old girl went, and the old girl is not going to come back.
- No safety gear, but those old girls certainly have a strong grip.
2.1An affectionate form of address to a girl or woman: he said, ‘Don’t worry, old girl’