Yidak - tibetain (Sanskrit : preta) "Hungry ghost" or "Tortured spirit". They are one of the most unfortunate classes of beings of the six realms of existence. Their world is characterised by the predominant emotion of greed. Yidaks suffer from hunger and thirst and a general inability to fulfil their desires. As a result they undergo intolerable suffering.

Yidam - tibetan A deity of accomplishments. They are a particular category of deity. A large and varied number of profound practices are related to them.