dumb terminal

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A terminal that has no internal microprocessor and thus no processing power independent of its host computer.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun computing A computer terminal consisting of a monitor (usually in monochrome) and keyboard, but (unlike a personal computer) having almost no processing capability, used to provide input to and receive output from a remote server, minicomputer, or mainframe.