[noncount] : the weight of the air in the Earth's atmosphere. the normal air pressure at sea level. atmospheric pressure. Pressure fell [=the air became lighter] as the storm approached. An area of high/low pressure [=heavy/light air] is moving over the west coast.
http://www.learnersdictionary.com/definition/pressure
Pressure (symbol: p or P) is the force applied perpendicular to the surface of an object per unit area over which that force is distributed. Gauge pressure (also spelled gage pressure) is the pressure relative to the local atmospheric or ambient pressure. Various units are used to express pressure.
https://en.wikipedia.org/wiki/Pressure
In the middle of a cyclone the air is generally still, but the great pressure of the wind on every side of the house raised it up higher and higher, until it was at the very top of the cyclone; and there it remained and was carried miles and miles away as easily as you could carry a feather.
http://legal-dictionary.thefreedictionary.com/pressure
Therefore, pressure is a scalar quantity, not a vector quantity. It has magnitude but no direction sense associated with it. Pressure acts in all directions at a point inside a gas. At the surface of a gas, the pressure force acts perpendicular (at right angle) to the surface.
https://en.wikipedia.org/wiki/Pressure
: the force that you feel when people are trying to persuade or force you to do something by using arguments, threats, etc. — see also peer pressure. [noncount]. He felt pressure from his father to become a doctor. = His father put pressure on him to become a doctor.
http://www.learnersdictionary.com/definition/pressure
The pascal is also a unit of stress and the topics of pressure and stress are connected. 1  Bed of nails (not really pressure but shear strain, which has the same units). 2  Finger bones are flat on the gripping side to increase surface area in contact and thus reduce compressional stresses.
http://physics.info/pressure/
Learner's definition of PRESSURE. 1. a: the weight or force that is produced when something presses or pushes against something else. — see also blood pressure. [noncount]. Keep steady pressure on the cap as you turn it. [=press on the cap as you turn it]. Apply pressure to the wound to stop the bleeding. the pressure of the compressed air inside the chamber. high/low water pressure [=a force that makes a flow of water strong/weak]. Check the car's tire pressure. [=the amount of air inside the tires].
http://www.learnersdictionary.com/definition/pressure
She was a frigate of great speed, fitted with high-pressure engines which admitted a pressure of seven atmospheres. 20,000 Leagues Under The Sea by Verne, Jules View in context. I brought such a pressure to bear on him that he naturally had to yield-he couldn't hold out.
http://legal-dictionary.thefreedictionary.com/pressure
Pressure may also be expressed in terms of standard atmospheric pressure; the atmosphere (atm) is equal to this pressure and the torr is defined as 1⁄760 of this.
https://en.wikipedia.org/wiki/Pressure
Some of these derive from a unit of force divided by a unit of area; the SI unit of pressure, the pascal (Pa), for example, is one newton per square metre; similarly, the pound-force per square inch (psi) is the traditional unit of pressure in the imperial and US customary systems.
https://en.wikipedia.org/wiki/Pressure
definition of  pressure
Pressure is the weight or force that is produced when something presses or pushes against something else.