Definition of "flaggy"

His flaggy wings when forth he did display, / Were like two sayles, in which the hollow wynd / Is gathered full […]

1590, Edmund Spenser, “Book I, Canto XI”, in The Faerie Queene. […], London: […] [John Wolfe] for William Ponsonbie

Yet it is reported, that in the Low Countries they will graft an apple cion upon the stock of a colewort, and it will bear a great flaggy apple, the kernel of which, if it be set, will be a colewort, and not an apple.

1631, Francis [Bacon], “(please specify |century=I to X)”, in Sylua Syluarum: Or A Naturall Historie. In Ten Centuries. […], 3rd edition, London: […] William Rawley; [p]rinted by J[ohn] H[aviland] for William Lee […]

If this view be correct there must have been a great difference in the sedimentation of the two areas, as the thick beds consist of alternations of flaggy sandstone with occasional true sandstone, almost pure limestones, calmstones, and few or no real flagstones.

1901, Geological Survey of Great Britain, Summary of Progress of the Geological Survey of Great Britain and The Museum of Practical Geology

In and out of the tufts they went, with their eyes dilating; wishing to be out of harm, if conscience were but satisfied. And of this tufty flaggy ground, pocked with bogs and boglets, one especial nature is that it will not hold impressions.

1869, R[ichard] D[oddridge] Blackmore, chapter VII, in Lorna Doone: A Romance of Exmoor. […], volume III, London: Sampson Low, Son, & Marston, […], page 111