1
[ verb ] get involved, so as to alter or hinder an action, or through force or threat of force

Examples

"Why did the U.S. not intervene earlier in WW II?"

Used in print

(Whit Masterson, Evil Come, Evil Go....)

Here 's where luck would normally step_in .

2
[ verb ] act as a substitute

Examples

"She stood in for the soprano who suffered from a cold"

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