What is the exact definition for high blood pressure or hypertension?

>140/90 or >130/85: Hypertension is when your blood pressure is >140/90, unless one has heart disease or diabetes, in which case the blood pressure should be <130/85.

Abnormally high BP: Current data suggest hypertension exists when ones blood pressure remains above 125/80. That is, there are adverse effects upon ones heart, brain and kidneys when ones blood pressure remains higher than this level of systolic and diastolic blood pressure.