Example : The team went into a slump.
A gradual slack in output.
A drop-off in attendance.
A falloff in quality.

Synonyms : falling off, falloff, slack, slump

Example : He stood on a high cliff overlooking the town.
A steep drop.

Synonyms : cliff, drop

Example : There was a decrease in his temperature as the fever subsided.
There was a sharp drop-off in sales.

Synonyms : decrease, lessening