Definition of ratting:
(n) :
(uncountable) A vocation involving the pest control of rats, typically using a working terrier.
(n) :
Desertion of one's principles.
(n) :
Working as a scab, against trade union policies.
(n) :
(archaic) The blood sport of setting a dog upon rats confined in a pit to see how many he will kill in a given time.