Definitions for onrushˈɒnˌrʌʃ, ˈɔn-
Random House Webster's College Dictionary
a strong forward rush, flow, etc.
Origin of onrush:
attack, onslaught, onset, onrush(noun)
(military) an offensive against an enemy (using weapons)
"the attack began at dawn"
a forceful forward rush or flow
"from the bow she stared at the mesmerising onrush of the sea where it split and foamed"; "the explosion interrupted the wild onrush of her thoughts"
A forceful rush or flow forward
An aggressive assault