A railroad tie (sleeper) that runs perpendicular to the rails to hold them at the correct distance apart.
From 'cross' (Old English 'cros', from Latin 'crux') and 'tie' (from Old English 'teag'). Emerged in 19th-century railroad terminology when standardized track construction required specific perpendicular support beams.
Railroad crossties prevented the most dangerous failure mode possible—if rails spread apart, a derailment was almost certain, so these humble wooden beams became literally the foundation of safe rail transport during the Industrial Revolution.
Complete word intelligence in one call. Free tier — 50 lookups/day.