(military) A call sign assigned in accordance with the provisions of the International Telecommunications Union to identify a radio station. The nationality of the radio station is identified by the first or the first two characters. (When used in visual signaling, international call signs are referred to as “signal letters.”)

(idiomatic) To ease up on after inflicting great punishment.

(computing) A technology that allows a computer program to cause a subroutine or procedure to execute in another address space, commonly on another computer on a shared network, without the programmer explicitly coding the details for this remote interaction.

(nautical) The first port that a vessel calls in at after the start of a voyage / (idiomatic) The first place to go to start a process.

plural of remote procedure call

plural of net call sign

plural of wake-up call

(idiomatic) To take action on the basis that another person is bluffing.

plural of reverse 911 call

To speak frankly about a given topic, not withholding one's opinions.