"Birth is dukkha, aging is dukkha, death is dukkha; sorrow, lamentation, pain, grief, & despair are dukkha; association with the unbeloved is dukkha; separation from the loved is dukkha; not getting what is wanted is dukkha. In short, the five aggregates for clinging/sustenance are dukkha."-- SN LVI.11
Dukkha is:Disturbance, irritation, dejection, worry, despair, fear, dread, anguish, anxiety; vulnerability, injury, inability, inferiority; sickness, aging, decay of body and faculties, senility; pain/pleasure; excitement/boredom; deprivation/excess; desire/frustration, suppression; longing/aimlessness; hope/hopelessness; effort, activity, striving/repression; loss, want, insufficiency/satiety; love/lovelessness, friendlessness; dislike, aversion/attraction; parenthood/childlessness; submission/rebellion; decision/indecisiveness, vacillation, uncertainty.
-- Francis Story in Suffering, in Vol. II of The Three Basic Facts of Existence (Kandy: Buddhist Publication Society, 1983)
"Both formerly & now, it is only dukkha that I describe, and the cessation of dukkha."SN XXII.86
"There are these three forms of stressfulness, my friend: the stressfulness of pain, the stressfulness of fabrication, the stressfulness of change. These are the three forms of stressfulness."See also:....
[Jambukhadika the wanderer:] "What is the path, what is the practice for the full comprehension of these forms of stressfulness?"
"Precisely this Noble Eightfold Path, my friend -- right view, right resolve, right speech, right action, right livelihood, right effort, right mindfulness, right concentration. This is the path, this is the practice for the full comprehension of these forms of stressfulness."
SN XXXVIII.14