Normal (adjective)

1. Conforming to a standard; usual, typical, or expected.
2. Conforming to a type, standard, or regular pattern.

Origin:

Late 16th century (in the sense "perpendicular to a surface"): from medieval latin normalis, from latin norma "rule, square".

Examples:

1. It's normal to feel nervous before a big exam.
2. His behavior is not normal, I think he needs help.
3. The weather is normal for this time of year.
4. It's normal for a baby to cry when they're hungry.
5. It's not normal to feel sick all the time.