means A small to medium bag, usually with a flap and a long strap worn over the shoulder, used for carrying books, papers, or odds and ends.

from From Old French 'sachel,' itself from Latin 'saccellus,' a little 'saccus' (sack or bag) — the same humble 'saccus' that gives us 'sack' and 'sac.' So beneath the strap and the dignity, the word is literally just a tiny sack, with the diminutive '-ellus' adding the only touch of refinement it ever earned.