Different fields of science use the term <answer>matter</answer> in different, and sometimes incompatible, ways. Some of these ways are based on loose historical meanings, from a time when there was no reason to distinguish mass and <answer>matter</answer>. As such, there is no single universally agreed scientific meaning of the word "<answer>matter</answer>". Scientifically, the term "mass" is well-defined, but "<answer>matter</answer>" is not. Sometimes in the field of physics "<answer>matter</answer>" is simply equated with particles that exhibit rest mass (i.e., that cannot travel at the speed of light), such as quarks and leptons. However, in both physics and chemistry, <answer>matter</answer> exhibits both wave-like and particle-like properties, the so-called wave–particle duality.
What term does science not have a universally-accepted scientific definition for?
matter