The Collaborative International Dictionary of English v.0.48:
Chalk \Chalk\ (ch[add]k), n. [AS. cealc lime, from L. calx
limestone. See Calz, and Cawk.]
1. (Min.) A soft, earthy substance, of a white, grayish, or
yellowish white color, consisting of calcium carbonate,
and having the same composition as common limestone.
2. (Fine Arts) Finely prepared chalk, used as a drawing
implement; also, by extension, a compound, as of clay and
black lead, or the like, used in the same manner. See
Black chalk, a mineral of a bluish color, of a slaty
texture, and soiling the fingers when handled; a variety
of argillaceous slate.
By a long chalk, by a long way; by many degrees. [Slang]
Chalk drawing (Fine Arts), a drawing made with crayons. See
Chalk formation. See Cretaceous formation, under
Chalk line, a cord rubbed with chalk, used for making
straight lines on boards or other material, as a guide in
cutting or in arranging work.
Chalk mixture, a preparation of chalk, cinnamon, and sugar
in gum water, much used in diarrheal affection, esp. of
Chalk period. (Geol.) See Cretaceous period, under
Chalk pit, a pit in which chalk is dug.
Drawing chalk. See Crayon, n., 1.
French chalk, steatite or soapstone, a soft magnesian
Red chalk, an indurated clayey ocher containing iron, and
used by painters and artificers; reddle.