This is the 10155th most frequent Turkish word.
başlamayan
"Başlamayan" means "that which has not started" or "not starting."
Here, 'başlamayan' describes a stage ('aşamada') that has not initiated yet, showing its descriptive function.
Proje hâlâ başlamayan bir aşamada bulunuyor.
The project is still at a stage that has not started.
'Başlamayan' modifies 'futbol maçı,' indicating that this particular event remains uninitiated.
Etkinlikler arasında başlamayan futbol maçı da vardı.
Among the events, there was also a soccer match that hadn't started yet.
In this sentence, 'başlamayan' qualifies 'işler,' indicating tasks or works that remain undone or unstarted.