E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
means the genus case, the case which shows the genus; thus, a bird of the air, of the sea, of the marshes, etc. The part in italics shows to what genus the bird belongs. Our s is the adjective sign, the same as the Sanskrit syâ, as udaka (water), udakasya (of water, or aquatic). So in Greek, demos (people), demo-sios (belonging to the people), or genitive demosio, softened into demo-io. In Chaucer, etc., the genitive is written in full, as The Clerkes Tale, The Cokes Tale, The Knightes Tale, The Milleres Tale, etc.