Definition of depend on/upon
1
:to be determined or decided by (something)
- We're not sure if we'll have the picnic. It depend s on the weather.
- "Will you go back to college?" "I don't know. It depends on whether or not I can afford it."
- The stamp's value depends on how rare it is.
- Depending upon your child's weight and height, she or he may have to sit in the back seat of the car.
2
:to need (someone or something) for support, help, etc.
- He no longer depends on his parents for money.
- They depend heavily/largely/solely/entirely on her income to pay the bills.
3
:to be sure about (someone or something) :to trust (someone or something)
- The manufacturer promises quality you can depend on.
- She will be remembered as a woman upon whom people could depend.
- I can always depend on it to rain on days when I forget my umbrella.
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