Callback

Part of speech: noun

Definitions

1. A function that is passed as an argument and executed after an initial operation completes ; a return signal sent to the caller in a telephone system to indicate call status
2. An operation that runs following the completion of another to handle results or continue processing ; a telephone system feature that sends a response back to the originator after call progress
3. A procedure triggered upon finishing a prior task to manage outcomes or events ; a communicated response in telephony that notifies the party who initiated contact of the call’s condition

Etymology: "Callback" is built from "call" and "back," and the noun is a deverbal formation, meaning it was derived from the phrasal verb "call back" rather than from the English words "call" and "back" joined together. The verb sense, to ring someone again or return a summons, is the older and more familiar one, and the noun grew out of it to name the thing that comes back in reply. The two senses in the definition sit on either side of that reply idea. In telephony, a callback is the return signal a system sends to the caller to report how a call is going, the ringing or engaged tone that answers the caller's attempt. In computing, it names a function handed to another routine as an argument, which that routine calls back once its own work is finished. Both uses share the same logic: something is sent out, and something answers it with a message.

Synonyms: return call, response, follow-up, recontact, recall