Cumulative frequency to a particular value of the variable either means the number of observations less than or equal to that value or the number of observations greater than or equal to that value.
Discrete and Continuous Variables were defined in the article An Introduction to Frequency Distributions. We shall continue our discussion on frequency distributions in this article by moving on to Frequency Distributions of Discrete and Continuous Variables.
To study the frequency distributions of a variable one needs to be familiar with a few preliminary concepts. These are explained here in this article.