Turnpike and Throughway

Turnpike noun - An expressway on which tolls are collected.

Throughway and turnpike are semantically related (American) In some cases you can use "Throughway" instead a noun "Turnpike".

Throughway noun - A broad highway designed for high-speed traffic.

Turnpike and throughway are semantically related in road topic. You can use "Turnpike" instead a noun "Throughway", if it concerns topics such as path upon which travel occurs.