Spreadsheet Definition
A spreadsheet is a rectangular table (or grid) of information, often financial information. (It is, therefore, a kind of matrix.) The word came from "spread" in its sense of a newspaper or magazine item (text and/or graphics) that covers two facing pages, extending across the center fold and treating the two pages as one large one.
The compound word "spread-sheet" came to mean the format used to present bookkeeping ledgers -- with columns for categories of expenditures across the top, invoices listed down the left margin, and the amount of each payment in the cell where its row and column intersect, for example -- which were traditionally a "spread" across facing pages of a bound ledger (= book for keeping accounting records) or on oversized sheets of paper ruled into rows and columns in that format and approximately twice as wide as ordinary paper.