Definition of "coldframe"

You can have the choicest foxglove, larkspur and cosmos only by aid of a coldframe.

1912, Seymour E. L. D, Garden Profits, page 106

Tomato seedlings will be ready to transplant from the hotbed to the coldframe in 12 to 18 days after sowing the seed, depending upon the amount of sunshine and the care given the bed. Sow them in late spring in the greenhouse or coldframe, but don't be tempted to sow any earlier otherwise they turn into triffids, hog all your greenhouse space and promote fungal diseases.

1924, Erval Jackson Newcomer, M. A. Yothers, Warren Draper Whitcomb, Control of the Codling Moth in the Pacific Northwest, page 11