The Collaborative International Dictionary of English v.0.48:
Pica \Pi"ca\, n. [L. pica a pie, magpie; in sense 3 prob. named
from some resemblance to the colors of the magpie. Cf. Pie
1. (Zool.) The genus that includes the magpies.
2. (Med.) A vitiated appetite that craves what is unfit for
food, such as clay, chalk, ashes, coal, etc.;
3. (R. C. Ch.) A service-book. See Pie. [Obs.]
4. (Print.) A size of type next larger than small pica, and
smaller than English.
Note: Pica is twice the size of nonpareil, and is used as a
standard of measurement in casting leads, cutting
rules, etc., and also as a standard by which to
designate several larger kinds of type, as double pica,
two-line pica, four-line pica, and the like.
Small pica (Print.), a size of type next larger than long
primer, and smaller than pica.