Origin: Latin suffix -ate
Interstate has 5 different meanings across 2 categories:
one of the system of highways linking major cities in the 48 contiguous states of the United States
"The driver merged onto the interstate to travel quickly from Chicago to Detroit."
A freeway that is part of the Interstate Highway System.
"We took a shortcut on the interstate to avoid the city traffic."
In plain English: An interstate is an official highway that connects different states across a country.
"The interstate is very busy during rush hour."
involving and relating to the mutual relations of states especially of the United States
"Interstate Highway Commission"
"interstate highways"
"Interstate Commerce Commission"
"interstate commerce"
Of, or relating to two or more states.
"The interstate highway system connects roads across multiple states."
In plain English: Interstate means something that involves travel between different states, like driving across state lines on a major highway.
"The interstate highway system connects cities across many states in America."
Usage: Use "interstate" as an adjective before a noun like highway or commerce to describe something connecting multiple U.S. states. Do not confuse it with "intrastate," which refers strictly to activities within a single state's borders.
Crossing states (usually provincial state, but also e.g. multinational sense).
"The truck driver spent twelve hours navigating the complex interstate route that connected three different provinces."
In plain English: Interstate means traveling from one state to another across country borders.
"She drove interstate to visit her family in another state."
Interstate combines the prefix inter- meaning "between" with state, originally functioning only as an adjective to describe things connecting different states. Its use as a noun, such as when referring to specific roads, arose later through ellipsis from the phrase "interstate highway."