eggshell

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. The thin, brittle, exterior covering of the egg of a bird or reptile.
2. n. A pale yellow to yellowish white.

Century Dictionary and Cyclopedia

1. n. The shell or outside covering of an egg: chiefly said of the hard, brittle, calcareous covering of birds' eggs. This shell consists mostly of carbonate or lime or chalk, deposited upon and in among the fibers of the egg-pod or putamen. It is a secretion of a particular calcific tract of the oviduct near the end of that tube. It may be nearly colorless and of such crystalline purity and translucency that the contents of the fresh egg show a pinkish blush through it, or very heavy, opaque, flaky white; whole-colored of various tones, as green, blue, drab, ochrey, etc.; or party-colored in many shades of reds, browns, etc., in endless variety of patterns. Besides the evident diversity of character in thickness, roughness, etc., the shell has many variations in microscopic texture, depending upon details of the deposition of the particles of lime in the pod. The shell of an ostrich's egg is so thick and hard that it may seriously wound a man if the egg explodes, as it sometimes does when addled, in consequence of the compression of the gases generated in decomposition.

Wiktionary

1. n. The shell around an egg.
2. n. A pale off-white colour, like that of the eggshell.
3. adj. Of a pale yellowish-whitish colour, like that of the eggshell.
4. adj. Exhibiting the thinness, translucency or near-transparency, and fragility of an eggshell; as in eggshell porcelain.

GNU Webster's 1913

1. n. The shell or exterior covering of an egg. Also used figuratively for anything resembling an eggshell.
2. n. (Zoöl.) A smooth, white, marine, gastropod shell of the genus Ovulum, resembling an egg in form.
3. adj. of a pale, yellowish-white color.
4. adj. (Architecture) having a smooth but not glossy texture like that of a hen's egg. Also referred to as matte glaze or non-lustrous glaze.

WordNet 3.0

1. n. the exterior covering of a bird's egg