A system is a regularly interacting or interdependent group of items forming an integrated whole. Every system is delineated by its spatial and temporal boundaries, surrounded and influenced by its environment, described by its structure and purpose and expressed in its functioning.
From then on, when anything went wrong with a computer, we said it had bugs in it.
RADM Grace Hopper, on the removal of a 2-inch-long moth from the Harvard Mark I experimental computer at Harvard in August 1945, as quoted in Time (16 April 1984)
A system is difficult to define, but it is easy to recognize some of its characteristics. A system possesses boundaries which segregate it from the rest of its field: it is cohensive in the sense that it resists encroachment from without...
Marvin Gerard Cline (1950). Fundamentals of a theory of the self: some exploratory speculations. p. 45.