1. A method of allowing multiple users to share a processor by allocating each user a portion of the processor resources on a timed basis and rotating each user's processes within those time segments. (Also, see Multitasking.) From I-gloss

2. A method of rotating processes that allows more than one user to have access to a computer system simultaneously. Each process is allocated a small segment of time in succession so that each user appears to have the computer to himself or hersel. From Linux Guide @FirstLinux