Question

In order for a new word to be maintained in your vocabulary, you must _______ it.

A. define
B. use
C. pronounce
D. read

Answer 1

In order for a new word to be maintained in your vocabulary, you must "use" it, but of course it should be noted that you should try to do all of these options as well. 

Answer 2

you should use it so it would be maintained in ur vocabulary ;)