form of program execution in which several programs are stored in main memory at same time and each program is executed as separate thread or process with execution chances on the processor being shared among them

A computer system operation whereby a number of independent jobs are processed together. Rather than allow each job to run to completion in turn, the computer switches between them so as to improve the use of the system hardware components.

The capability to process many programs concurrently for multiple users. Memory is divided and then allocated to the programs being processed concurrently.

the execution of two or more computer programs by a single computer

Concurrent execution of several different programs by sharing the same central processing unit (CPU).

(n.) the ability of a computer system to time share its (at least one) CPU with more than one program at once. See also multitasking.