1932, "a communication system of teletypewriters," from tel(etype) ex(change).
"act or process of reducing to a code or system," 1817 (Bentham), noun of action from codify.
1670s, "pertaining to a system," from French systématique or directly from Late Latin systematicus, from Greek systematikos "combined in a whole," from systema (genitive systematos); see system. From 1789 as "methodical," often in a bad sense, "ruthlessly methodical." Related: Systematical (1660s); systematically.