The apical buds, axillary buds, underground structures like rhizomes, tubers etc. undergo a period of suspended growth under unfavourable season that is during the winter season. So this dormancy of buds is known as the bud dormancy.
Bud dormancy is the suspension of the physiological process and growth which can be reactivated. The bud dormancy is induced by the environmental conditions such as the seasonality or extreme heat, drought or cold.