CAS may refer to any of the following:
1. Short for column address select or column access strobe, CAS is a signal that your CPU or other hardware device such as a video card sends to the RAM. The signal contains information about what column in computer memory has the data being requested.
2. The CAS latency or CL is the total time it takes for the memory controller in a hardware device to send a request to and receive a response from a column of memory.