SLAKE, AS THIRST is a phrase that means to QUENCH one's thirst. It is an old-fashioned term that is still used in some parts of the world today. The word 'SLAKE' is derived from the Old English word 'sleac, ' which means to extinguish or put out. The phrase 'as thirst' is used to emphasize the need to QUENCH one's thirst. Therefore, SLAKE, AS THIRST is a phrase that means to QUENCH one's thirst in a very urgent manner.