1) A knife or dagger used to deliver a coup de grace; the word was also used for a particularly slender knife designed specifically to pass through the gaps in a knight's visor. [< Lat. misereor = to have pity] -
Cf. Ocularium
2) In pre-11c English churches, it was forbidden to sit down: there were no seats in the part of the church or *cathedral for the lay congregation; nor were there any for monks or canons. However, this practice eased during the 12c. Initially, *leaning staffs were permitted for the frail. Later, seats were added to the stalls. In time a further act of mercy was allowed by adding to the underside of the raised choir seat a small ledge, which gave some support. Misericord in this context was taken to mean an 'indulgence seat'. The earliest surviving misericords are to be found at Exeter Cathedral, dating from 1255-79. [< Lat. misereor = have pity]
3) Monks were forbidden meat, except in the infirmary. By the 13c, a kind of half-way house emerged between *frater and infirmary where meat could be eaten, i.e. the misericord or chamber of mercy. At Peterborough it was called the 'seyny house' (seyny < seynen = to make the sign of the cross, to bless). Later, this arrangement was further amended so that half the members of a monastery were permitted meat and the others not. It marked the waning of the fervour of the original revival of faith and the softening of the order's rules. -
Cf. Calefactory
Dictionary of Medieval Terms and Phrases. Christopher Coredon with Ann Williams.