There are several different definitions for this particular word, with all still being widely used to this day.
The first definition is something that disgusts, or causes dislike, for example his attitude fair scunners me. The second usage describes the actual feeling of disgust or dislike. It’s unclear whether some definitions of this word stem from the word ‘sickener’ or whether the similarities in pronunciation and meaning are coincidental. The final definition is used for someone or something who causes the dislike or disgust, such as It’s a right scunner that the match has been cancelled ‘cause of the weather.’ This particular word is used widely, with the original meaning – to shrink back, or recoil – falling by the wayside somewhat, in preference for the more generic term we know today.