What is meant by bimodal distribution?

Answer 1

You are likely familiar with the probability density function of the normal distribution--that is, the bell-shaped curve.

A bimodal distribution is one whose probability density function has two 'humps' or maxima. In other words, values of the random variable are more likely to occur around where those two maxima occur than elsewhere, in the same way that values of a normally distributed random variable are more likely to occur around its maximum.