A couple of dictionary definitions state "unusual in an attractive and interesting way" and "characterised by peculiar or unexpected traits or aspects".
In a golfing sense, for us anyway, it is something that swerves from the norm, has elements of eccentricity, is unique and is often found in unconventional natural landforms. Most importantly quirk promotes good and stimulating golf without ever crossing the line to become too outlandish, nonsensical and gimmicky.
Golf Empire founder, Ed Battye, has played extensively throughout Great Britain & Ireland and below he gives his top quirky courses.