If a guy refers to a girl as 'lady friend' - what does that mean?

Hi Guys.

Today a girl in my class asked a guy in my class if he had seen his 'lady friend' last night. he answered 'perhaps' with a smirk on his face.

English is not my first language, so what does that mean?

Is this simply a girlfriend he is in a relationship with? He never posted anything about her on Facebook, no pictures and no relationship status or anything. and he is Facebook addicted, on it 24/7.

Or do men refer to a girl they are seeing as a lady friend first, before they fully commit?

Thanks :)

Updates
+1 y
the thing is he never said lady friend. the girl asked about his lady friend. but he says he is seeing someone, but is still single..
If a guy refers to a girl as 'lady friend' - what does that mean?
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