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"
the occurrence of incoming water (between a low tide and the following high tide); "a tide in the affairs of men which, taken at the flood, leads on to fortune" -Shakespeare
any backward region that is isolated from the world and resists progress
a body of water that was created by a flood or tide or by being held or forced back by a dam; "the bayous and backwaters are breeding grounds for mosquitos"