A noticeable deterioration in performance or quality:
— A drop-off in attendance.

synonyms: falling off, falloff, slack, slump.

A steep high face of rock.

synonyms: cliff, drop.

Dutch: klif, klip
Polish: klif, faleza

A change downward:
— There was a sharp drop-off in sales.

synonyms: decrease, lessening.

Dutch: terugloop
Polish: zmniejszenie się, zmalenie, pomniejszenie się