Economists are at fault. Am sure they are the ones to coin this one. And now they are struggling to convince governments and policy-makers. And struggling to make the common man understand the significance of all that falls under this term 'externality'.
Imagine, the environment we are surrounded by is captured in this term 'externality'. Of course, the term is derived from 'external'. Quite amazing that in our pursuit of convenience, the very things which ensure our survival, are conceptually thought of as 'external'.