Definition of "merlin"

The gentle falcon, that with its feet distraineth / The kingës hand; the hardy sperhawke eke, / The quailës foe; the merlion that paineth / Himself full oft the larkë for to seek; [...]]

Laing Purves, editor, The Canterbury Tales and Faerie Queene: With Other Poems of Chaucer and Spenser. […], Edinburgh: William P. Nimmo, 1874, page 220, column 2

Smaller and less powerful falcons included the merlon, the hobby, and the kesterel.

1991, Thomas S. Henricks, “Sport in Feudal England”, in Disputed Pleasures: Sport and Society in Preindustrial England (Contributions to the Study of World History; 28), Westport, Conn.: Greenwood Press, Greenwood Publishing Group, page 23