'heavily-trafficked' originates from the combination of 'heavy' and 'traffic,' where 'heavy' meant 'great in amount' and 'traffic' referred to 'movement of vehicles or people.'

'heavily-trafficked' evolved from the combination of 'heavy' and 'traffic' in modern English to describe areas with significant movement.

Initially, it meant 'areas with significant movement,' and this meaning has largely remained the same in modern usage.