If you are trying to make something smaller, do you use the word “reduce,” or do you use “shorten” or “decrease”? As the old-timer petroleum engineer would always answer: “That depends.”
Use the word “shorten” if the thing being made smaller is distance or time. Take a look at the units of measure of the thing. If it’s in., cm, ft, m, miles, km or other units of length, or if it’s sec, min, hr, days, weeks, months, or years, then use “shorten.”
OSHA says we will have to shorten the distance from the living quarters to the lifeboats.
Flowback is used to shorten fracture closure times in extremely tight formations.
Use the word “reduce” if you wish to diminish the size, amount, extent or number. Using the word “decrease” implies a progressive decline over a period of time.
If you want to decrease your waistline, you will need to reduce the number of calories in the food you consume.
Here, the caloric reduction happens all of a sudden, but the waistline getting smaller takes time.
Some examples of things that are reduced all of a sudden are: risk, prices, workforces. Some things that are decreased with time are populations in rural areas, drop-out rates in schools, and the number of Americans majoring in science and engineering.