main line(redirected from Pennsylvania Main Line)
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(Russian, magistral’; from Latin magistralis, “leading”).
(1) The main route, the primary line in communications (railroad main line, waterway main line).
(2) A wide and heavily traveled street in a large city.
(3) The main cable or wire in an electrical circuit or in tele-graph and telephone communications.
(4) The main pipe in a sewerage line or water system.