Underground railroad ∨ railway Meaning, Definition & Usage

Definitions
  1. . (a) A railroad or railway running through a tunnel, as beneath the streets of a city . (b) Formerly, a system of coöperation among certain active antislavery people in the United States, by which fugitive slaves were secretly helped to reach Canada . In the latter sense railroad, and not railway, was used.
    "Their house was a principal entrepôt of the underground railroad." W. D. Howells.
Definitions
  1. . See under Railroad.

Webster 1913