Normal's
来自Big Physics
mid 17th century (in the sense ‘right-angled’): from Latin normalis, from norma ‘carpenter's square’ (see norm). Current senses date from the early 19th century.
mid 17th century (in the sense ‘right-angled’): from Latin normalis, from norma ‘carpenter's square’ (see norm). Current senses date from the early 19th century.