This is the 717th most frequent Bulgarian word.
бившият
"The former" or "ex-" (used to refer to a previous partner, position, or status).
The word "бившият" refers to someone who previously had a certain role or position in relation to the speaker, in this case a former colleague.
Бившият ми колега сега работи в друга компания.
My former colleague now works at another company.
"Бившият" indicates a person who no longer holds the title mentioned afterward, here referring to the former mayor.
Бившият кмет на града беше много популярен сред гражданите.
The former mayor of the city was very popular among the citizens.
Here, "бившият" specifies a previous relationship status, designating someone as an ex-spouse.