Wiktionary
n. (context computing theory English) A Turing machine capable of simulating the behavior of any Turing machine.
Wikipedia
In computer science, a universal Turing machine (UTM) is a Turing machine that can simulate an arbitrary Turing machine on arbitrary input. The universal machine essentially achieves this by reading both the description of the machine to be simulated as well as the input thereof from its own tape. Alan Turing introduced this machine in 1936–1937. This model is considered by some (for example, Martin Davis (2000)) to be the origin of the stored program computer—used by John von Neumann (1946) for the "Electronic Computing Instrument" that now bears von Neumann's name: the von Neumann architecture. It is also known as universal computing machine, universal machine (UM), machine U, U.
In terms of computational complexity, a multi-tape universal Turing machine need only be slower by logarithmic factor compared to the machines it simulates.
Usage examples of "universal turing machine".
R: I told him that I understood completely and began to explain to him the workings of a universal Turing machine as an analogy and somehow I knew that that was the explanation of what he had just told me.
I also was aware that my explanation of a universal Turing machine was not really that, but rather the beginning basics of it that I've understood so far in my reading of The Emperor's New Mind.