Meaning of ball signal | Babel Free
Definitions
A kind of mechanical signal used on early American railroads, consisting of wooden balls, painted various colors, that were hoisted up and down a pole using a rope and pulley.
historical
CEFR level
B2
Upper Intermediate
This word is part of the CEFR B2 vocabulary — upper intermediate level.
This word is part of the CEFR B2 vocabulary — upper intermediate level.