open–ended

open–ended /ˌoʊpənˈɛndəd/ adjective
open–ended
/ˌoʊpənˈɛndəd/
adjective
Britannica Dictionary definition of OPEN–ENDED
1 
: able to change : not ending in a certain way or on a certain date
2 
: allowing people to talk in a way that is not planned or controlled