Sackless comes from Old English sacleas ('free from guilt or dispute'), from sacu ('strife, lawsuit, guilt') + -leas ('-less'); related to the word sake. The historical chain includes Old English sacleas and Old English sacu. The quoted older senses, "free from guilt or dispute", "strife, lawsuit, guilt", and "-less", supply the semantic anchors for sackless. The formation is best read as suffixal and borrowed: the word sackless carries its older form-history into a compact English lexical shape. In present English it is used as a adj, "innocent or guiltless; also dialectally feeble or simple-minded". Related English forms include sake. The result is a adj whose etymology preserves both the older form and the later English specialization.