What is a good word to use for when something is rapidly decreasing or lowering?

hi AngelPassion
Deflating, plummeting, nose diving, crashing, descending, sinking, bombing, collapsing.
In future goole antonyms of the word.

here: http://englishthesaurus.net/antonym/increase

Antonyms for increase

Antonyms for (noun) increase

Main entry: step-up, increase
Definition: the act of increasing something
Usage: he gave me an increase in salary
Antonyms: decrease, diminution, reduction, step-down
Definition: the act of decreasing or reducing something

Main entry: increase, increment
Definition: the amount by which something increases
Usage: they proposed an increase of 15 percent in the fare
Antonyms: decrease, decrement
Definition: the amount by which something decreases

Main entry: increase
Definition: a change resulting in an increase
Usage: the increase is scheduled for next month
Antonyms: decrease, drop-off, lessening
Definition: a change downward
Usage: there was a decrease in his temperature as the fever subsided; there was a sharp drop-off in sales

Main entry: increase, increment, growth
Definition: a process of becoming larger or longer or more numerous or more important
Usage: the increase in unemployment; the growth of population
Antonyms: decrease, decrement
Definition: a process of becoming smaller or shorter



Antonyms for (verb) increase

Main entry: increase
Definition: make bigger or more
Usage: The boss finally increased her salary; The university increased the number of students it admitted
Antonyms: lessen, minify, decrease
Definition: make smaller
Usage: He decreased his staff

Main entry: increase
Definition: become bigger or greater in amount
Usage: The amount of work increased
Antonyms: fall, lessen, diminish, decrease
Definition: decrease in size, extent, or range
Usage: The amount of homework decreased towards the end of the semester; The cabin pressure fell dramatically; her weight fell to under a hundred pounds; his voice fell to a whisper

best wishes
:)