1 [intransitive and transitive]
to become wider, or to make something wider [≠ narrow]:
They're widening the road.
The river widens and splits.
2 [intransitive and transitive]
to become larger in degree or range, or to make something do this [≠ narrow]:
The gap between income and expenditure has widened to 11%.
They are trying to widen the discussion to include environmental issues.
if your eyes widen, they open more, especially because you are surprised or frightened