Different fields of science use the term matter 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 <answer>mass</answer> and matter. As such, there is no single universally agreed scientific meaning of the word "matter". Scientifically, the term "<answer>mass</answer>" is well-defined, but "matter" is not. Sometimes in the field of physics "matter" is simply equated with particles that exhibit rest <answer>mass</answer> (i.e., that cannot travel at the speed of light), such as quarks and leptons. However, in both physics and chemistry, matter exhibits both wave-like and particle-like properties, the so-called wave–particle duality.
Sometimes scientific terms were historically considered in ways we know now aren't compatible because scientists didn't need to distinguish matter from what other term?
mass