c. 1400, pulpe, "fleshy part of a fruit or plant," from Latin pulpa "animal or plant pulp; pith of wood," earlier *pelpa, perhaps from the same root as pulvis "dust," pollen "fine flour" (see pollen). Extended to similar moist substances or masses by early 15c.
From 1727 as "the material from which paper is manufactured after it is reduced to a soft, uniform mass." The adjective meaning "sensational" is from pulp magazine (1931), so called from wood-pulp paper in sense of "type of rough paper used in cheaply made magazines and books," and thus, in reference to publications made of it (the opposite adjective in reference to magazines was slick). As a genre name, pulp fiction is attested by 1943 (pulp writer "writer of pulp fiction" was in use by 1939).
1660s (implied in pulping), "reduce to pulp, made into pulp," from pulp (n.). As "to remove the pulp from, deprive of the surrounding pulp" from 1791. Related: Pulped.