Given the definition of an ordinary point:
Given a Second Order homogenous Linear Differential Equation a2(x)y″+a1(x)y′+a0(x)y=0⊛ rewritten in standard form as y″+P(x)y′+Q(x)y=0
x0 is an ordinary point of ⊛ if P(x) and Q(x) are both analytic at x0
If x0 is not an ordinary point, it is called a singular point of ⊛.