What is a polynomial... In general 'poly' means many and 'nomials' means terms. That means polynomial means having many terms. But this is not the definition, it's just the meaning of the word.
Now we will define what is a polynomial,
Before going to define, first we define what do we mean by an algebraic expression. It's an important word which we use in maths.
ALGEBRAIC EXPRESSION :
Its a mathematical statement which has combination of variables and constants connected by some or all the arithmetic operations like +,-,x, / etc.
Ex. x+2, y^2-2x+√x etc
POLYNOMIALS:
It's an algebraic expression in which the powers of the variables are non negative integers(whole numbers).
Ex. x^2+2x^2.y^2-6 it is a polynomial
x^-2 +x-2 it is not a polynomial, because the power of the variable X is negative.
**For an algebraic expression to be a polynomial
1.The exponent of the variable should be a whole number.
2.There should be no variable in the denominator.
3.A polynomial may contact in n any number of terms but it should have definite number of terms.