The word teraflop combines tera, which is a prefix from the International System of Units used to denote one trilion (1,000,000,000,000), with flop, which is an acronym of Floating Point Operations Per Second.
You can make an analogy with the number of instructions per second that can be handled. Flops are mainly used to measure the performance of supercomputers. IBM’s BlueGene/P, one of the fastest in the world, is capable of processing over 1,000 teraflops.
IBM’s prototype was benchmarked at 70.72 trillion calculations per second, or teraflops, using the Linpack benchmark, which puts the system through a series of mathematical calculations. (PC Woirld in 2005)
To get to a teraflop it will be necessary to harness tens of thousands of microprocessor chips in parallel into a reliable supercomputer and to add a phenomenal amount of memory. (NY Times)