Definition of "mealy"

That it is a cross-breed there can be no doubt, from the fact that after a year or two the brilliant colours, both orange and black, begin to fade—the orange fading into a mealy tint, and the black to a dingy grey.

1875, The Bird-Keeper's Guide and Companion, page 19

I know not, indeed, if the artist could give the beautiful orange which distinguish [sic] the jonque, or the mellowness of tint that pervades the mealy.

1800, The New and Complete Canary-bird Fancier, page 8

The clear Norwich canaries, as well as the evenly marked, the crested, the ticked, the green, and the unevenly marked, are each divided into two separate classes, i.e., jonques and mealies.

1884, Robert Linlithgow Wallace, The Canary Book, page 225