syntax (n.)

1620s, "science of arranging military forces for combat," from Modern Latin tactica (17c.), from Greek taktikē tekhnē "art of arrangement," noun use of fem. of taktikos "of or pertaining to arrangement," especially "tactics in war," adjective to taxis "arrangement, an arranging, the order or disposition of an army, battle array; order, regularity," verbal noun of tassein "arrange" (from PIE root *tag- "to touch, handle").

1771, "conjoined, fitted to each other," from Modern Latin syntacticus, from Greek syntaktikos "a joining together, a joining in order," from syntassein "put in order" (see syntax). The meaning in grammar, "pertaining to or according to syntax," is by 1807; earlier in this sense was syntactical (1570s). Psychology tended to use syntaxic (1945).