1) Block of stone used as the base of e.g. a market cross or similar. [< Fr. pierre = a stone] -
Cf. Eleanor crosses
2) Not unlike the previous entry, this was sometimes a mound, sometimes a pillar, which featured in the more elaborate writings and practices of knightly contests. Its use at real tournaments may have been taken from Chretien de Troyes's Ywain (c.1170-80) in which it served as the place where challenges were made; or if a pillar, where shields were hung waiting to be touched, which action served as the challenge. Sometimes there was a horn to be sounded to mark the challenge. -
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.