Why is matter called matter?

Answer 1

Brain tissue is called gray matter because it is gray.

Answer 2

Because it means a substance, something from which stuff is made or what was at the origin, it is the inner core of a tree. In chemistry, it is a substance, which is something that must occupy space and have its own mass. Interestingly enough, it has the same root (etymologically) as the word mother.

Etymology: matter (n.)

c. 1200, materie, "the subject of a mental act or a course of thought, speech, or expression," from Anglo-French matere, Old French matere "subject, theme, topic; substance, content; character, education" (12c., Modern French matière) and directly from Latin materia "substance from which something is made," also "hard inner wood of a tree." According to de Vaan and Watkins, this is from mater "origin, source, mother" (see mother (n.1)). The sense developed and expanded in Latin in philosophy by influence of Greek hylē (see hylo-) "wood, firewood," in a general sense "material," used by Aristotle for "matter" in the philosophical sense.

The Latin word also is the source of Spanish, Portuguese, and Italian materia, Dutch, German, and Danish materie, vernacular Spanish madera, Portuguese madeira "wood" (compare Madeira). The Middle English word also sometimes was used specifically as "piece of wood."