a floating position on one’s back with arms extended out to the sides and face upward.
a flow of a liquid opposite to the usual or desired direction.
- Backflow valve
backwater valve. a valve for preventing flowing liquid, as sewage, from reversing its direction.
- Back focus
the distance between the back surface of a lens and the focal plane when the lens is focused at infinity.
- Back foot
noun on the back foot, at a disadvantage; outmanoeuvred or outclassed by an opponent Contemporary Examples Government forces, he says, are constantly on the back foot, rarely launching offensives to regain territory. Iraqis Swear: Baghdad Airport is Safe From ISIS Susannah George October 12, 2014 Historical Examples He pulled at his back foot like a […]