What is "piepowder"

Piepoudre \Pie"pou`dre\, Piepowder \Pie"pow`der\, n. [Lit., dustyfoot, i. e., dusty-footed dealers, fr. F. pied foot + poudreux dusty.] (O. Eng. Law) An ancient court of record in England, formerly incident to every fair and market, of which the steward of him who owned or had the toll was the judge.
--Blackstone.

early 13c., "wayfarer, itinerant merchant, etc.," folk etymology alteration of Old French pie pouldre or Medieval Latin pede-pulverosus, both literally "dusty-footed" (see foot (n.) + powder (n.)).

n. (context UK legal obsolete English) An ancient court of record in England, formerly incident to every fair and market, of which the steward of him who owned or had the toll was the judge.