<testing> Testing that is transparent to the software under test, i.e., does not change its timing or processing characteristics. Nonintrusive testing usually involves additional hardware that collects timing or processing information and processes that information on another platform.
Try this search on Wikipedia, OneLook, Google
Nearby terms: Nondeterministic Turing Machine « non-impact printer « non-interlaced « nonintrusive testing » nonlinear » Non-Maintainer Upload » Non-Maskable Interrupt