Learner's definition of REPLACEMENT
the act of replacing something
She underwent a hip replacement. [=a doctor replaced her hip with an artificial hip]
Is your old dictionary in need of replacement? [=do you need a new dictionary?]
Your car's replacement cost is less than the cost to repair it. [=it costs less to buy a new car than it does to fix your car]
a person or thing that replaces someone or something else
I'm training my replacement.
We need a replacement for our old vacuum cleaner.
Where can we get replacement parts for the tractor?