When to use "lessen", when "decrease", and when "reduce"? [closed]

Is it appropriate to say this:

1. I need to reduce the amount of money I spend per month.
2. I need to lessen the amount of money I spend per month.
3. I need to decrease the amount of money I spend per month.

I don't understand when to use "reduce", "decrease", and "lessen". Can you explain it, please?

Solution 1:

Offhand I can't think of any contexts where the choice between reduce, lessen, decrease would make any difference to the meaning of an utterance. But there are significant differences as regards how common each verb is...

Note that the above chart shows the transitive usage (someone or something causes the amount to become smaller). But here's another chart showing the intransitive usage (the amount still becomes smaller, but no "agent" is specified)...

...where you'll note that lessen doesn't even occur often enough to chart.

My advice for learners would be to avoid using lessen at all (as this chart shows, it's been falling in popularity for at least three centuries).

As regards the choice between the other two, it's pretty obvious reduce is significantly more common. But no-one would be likely to think you'd made an "uncommon, unusual" choice if you used decrease instead (particularly in intransitive contexts), so it doesn't really matter which one you use. There's no doubt that decrease has been gradually gaining traction, but it still lags well behind reduce.