Dukkhatā: abstr. noun fr. dukkha 'the state of suffering', painfulness, unpleasantness, the unsatisfactoriness of existence.,There are three kinds of suffering: 1 suffering as pain dukkha-dukkhatā 2 the suffering inherent in the constructions sankhāra-dukkhatā 3 the suffering in change viparināma-dukkhatā see: XLV, 165; D. 33.
1 is the bodily or mental feeling of pain as actual]y felt. 2 refers to the oppressive nature of all constructions of existence i.e. all conditioned phenomena, due to their continual arising and passing away; this includes also experiences associated with neutral feeling. 3 refers to bodily and mental pleasant feelings,;because they are the cause for the arising of pain when they change; Vis.M XIV, 34f.
Maha Thera Nyanatiloka. Manual of Buddhist Terms and Doctrines, Buddhist Publication Society, first edition 1952.