Definition of make certain
- Make certain (that) you lock the door when you leave.
- We must make certain this doesn't happen again.
- She made certain she thanked each of them for coming.
: behave, act
: to begin or seem to begin (an action)
: to cause to happen to or be experienced by someone
: the manner or style in which a thing is constructed
: the physical, mental, or moral constitution of a person
: fixed, settled
: of a specific but unspecified character, quantity, or degree
: dependable, reliable
: certain ones
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