What is abscissic acid and why it is called as stress hormone?

Abscisic acid is a mildly acidic growth hormone, which functions as a general growth inhibitor by counteracting other hormones or reactions mediated by them.
Abscissic acid is also called as stress hormone because the synthesis of abscissic acid is stimulated by drought, water logging and other adverse environmental conditions. It is produced in many parts of the plants but more abundantly inside the chloroplasts of green cells.