Define Thrust and Pressure.

Hint: This question is totally based on our understanding of Thrust and pressure. In order to define it, we need to understand the concept of force, area, and perpendicular or normal force acting on a body. Then by relating them we can give the definition of thrust and pressure.

Complete answer:
First of all we need to find out the meaning of force, area and perpendicular force.
Force: As we know that force is the pull or push when applied on a body makes the body change its position or shape. It depends on the mass and acceleration of the body. Mathematically, it is given by, $F = ma$
Area: The space occupied by any surface of an object or body is known as the area of that body. It depends on the shape of the body or object.
Perpendicular Force: When the force is applied at ${90^\circ }$to the object, then it is known as perpendicular force.
Now we can define Thrust.
Thrust is defined as the perpendicular force applied per unit area on a body. Mathematically, it is given as,$Thrust = \dfrac{{{F_{perpendicular}}}}{A}$.
And we can define pressure as the force applied per unit area on a body. Mathematically, it is given as,
$P = \dfrac{F}{A}$

Note: We should also know this fact that pressure or thrust is inversely proportional to the area on which it is acting. More the area less will be the pressure exerted by the body. And if the area of the body will be less, then more pressure will be exerted on the body.