english
1
general::
Be useful or convenient, as in This check will really come in handy. [Mid-1800s] Also see COME IN, def. 4.
American Heritage Idioms
2
general::
Phrase(s): come in handy [for something] to be useful. • I think that this gadget will come in handy in the kitchen.
McGrawhill's American Idioms And Phrasal Verbs