Statistics a bar graph in which the area of each bar is proportional to the frequency or relative frequency represented
histo(ry) + -gram
See histogram in American Heritage Dictionary 4
A bar graph of a frequency distribution in which the widths of the bars are proportional to the classes into which the variable has been divided and the heights of the bars are proportional to the class frequencies.
Origin: Greek histos, mast, web; see stā- in Indo-European roots