Dictionary of Biblical Words:
The narrow path or the Lord’s path
is frequently used to mean the path of separation from this world in which the Christian is called to walk. The only danger specially connected with it is a “narrow mind,” which arises from walking in the path without Christ.
Strong’s Dictionary of Greek Words:
Meaning:
from 5164; a track (as a wheel-rut), i.e. (figuratively) a course of conduct