Definition of "colourable"

Doth the master make any bargaine, or dispatch that pleaseth not? it is immediately smothered and suppressed, soone after forging causes, and devising colourable excuses, to excuse the want of execution or answer.

1603, Michel de Montaigne, chapter 8, in John Florio, transl., The Essayes […], book II, London: […] Val[entine] Simmes for Edward Blount […]

they told him their comming was for some extraordinary tooles and shift of apparell; by this colourable excuse, they obtained 6. or 7. more to their confederacie […].

1612, John Smith, Proceedings of the English Colonie in Virginia, Chapel Hill 1988 (Select Edition of his Writings), p.178

These three examples have what may be called a 'colourable' claim for a public justification: they do not appear to us as checkerboard statues because, looking at the distinctions they draw, we presume the required justification does exist.

2003, Ofer Raban, Modern legal theory and judicial impartiality, page 83

Glauce, what needs this colourable word, / To cloke the cause, that hath it selfe bewrayd?

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

This matter, however, is not itself coloured, but is only capable of exhibiting colours, by the addition of other matters : and hence we have ventured to call it the colourable, rather than the colouring parts of the plant, by which we merely indicate its property of becoming coloured, but not its actual possession of colour.

1811, Daniel Ellis, Farther inquiries into the changes induced on atmospheric air, by the germination of seeds, the vegetation of plants, and the respiration of animals, page 117

These results were discovered whilst investigating uniquely edge colourable graphs.

1978, A. G. Thomason, “Hamiltonian Cycles and Uniquely Edge Colorable Graphs”, in Advances in graph theory: Volume 1977, page 259

A circle graph with no cycle of length four is colourable with three colours.

1992, A. Finkel, M. Jantzen, editors, STACS 92, 9th Annual Symposium on Theoretical Aspects of Computer Science, page 397

Take a look at the free colouring page application available at Kidopo […] This service offers all the essential colouring tools _[sic] a pen, a pencil, colouring palette etc _ and presents a variety of colourable pictures for helping the child simulate a real colouring experience.

2010 October 4, J Murali, “Online document sharing: expanding frontiers”, in The Hindu