origins

Spreadsheets earned their name before the period of computers. Paper-based spreadsheets were used by businesses to plan for the future. They consisted of numbers "spread" over a grid on the paper.
The planning activity involved frequent amendments and laborious recalculation every time there was a change in the data used to do the planning or forecasting activity.

Traditionally the columns of the grid represented a time period of a day, week, month or year.