(logic) A set of axioms and a set of inference rules which are jointly used to deduce tautologies, thereby providing proofs of them.

plural of product differentiation

(economics, marketing) Perceived differences between the product of one firm and that of its rivals so that some customers value it more.

Graph paper with vertical and horizontal rules, the latter spaced evenly and the former according to a scale that allows a plotted probability curve — usually that of a normal distribution — to appear linear.

(statistics) The bias to meta-analysis resulting from statistical studies with low statistical power tending to remain unpublished and inaccessible to the analyst.

(computing) A child process that has terminated but is still listed in the process table, having not yet been reaped by its parent process.

(anatomy) A protrusion from the rest of the skull, most of it belonging to the zygomatic bone, but also contributed to by the frontal bone, maxilla and temporal bone.

(of a knot k) That no nontrivial Dehn surgery along k in the 3-sphere yields a simply connected manifold.

Alternative spelling of proof of concept

plural of universal product code