Английский Этимологический словарь - congress

- 14c., from L. congressus "a meeting, hostile encounter," pp. of congredi "meet with, fight with," from com- "together" + gradi "to walk," from gradus "a step." Sense of "meeting of delegates" is first recorded 1678. Meaning "sexual union" is from 1589. Used for the national legislative body of the American states since 1775.