Despite the frequency with which stress is used in
everyday language, it is surprisingly difficult to define.
It is a term that lends itself to subjectivity and emotiveness
and can appear diffuse and lacking in certainty
of meaning. We developed a working definition of
stress that is “a complex physiological state that embodies
a range of integrative and behavioral processes
when there is a real or perceived threat to homeostasis”
(Tilbrook and Clarke, 2006, p. 285; Tilbrook, 2007).