means A person who studies or works professionally in mathematics — the abstract science of numbers, structures, shapes, and patterns.

from From Greek mathēmatikos, 'fond of learning,' which traces back to the verb manthanein, 'to learn.' The root noun mathēma simply meant 'that which is learned' — knowledge itself. So a mathematician was once, quite literally, just 'one who learns,' before the word narrowed to those who learn the most relentless subject of all. It reached English through Latin mathematicus and Old French, arriving by the late Middle Ages.