1) The son of Adam, and the killer of his brother, Abel. For that crime he was banished, thus becoming a wanderer and archetype of pilgrims. However, the medieval person would also know that before his crime, Cain was 'the tiller of the land' (Genesis 4:2) while Abel was 'the keeper of sheep'. With Abel dead by his brother's hand, the land was cursed and barren: 'When thou tillest the ground, it shall not henceforth yield unto thee her strength; a fugitive and a vagabond shalt thou be in the earth.'
Cf. Cayme
2) Tribute of food and other produce in 13c Ireland and Scotland, which might also include for example an otter skin. Not to be confused with Adam's son and Abel's brother.
Cf. Caitiff.
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.