early 15c., in reference to certain eminent justices of the peace, from Latin quorum "of whom," genitive plural (masc. and neuter; fem. quarum) of qui "who" (from PIE root *kwo-, stem of relative and interrogative pronouns). The traditional wording of the commission appointing justices of the peace translates as, "We have also assigned you, and every two or more of you (of whom [quoram vos] any one of you the aforesaid A, B, C, D, etc. we will shall be one) our justices to inquire the truth more fully." The justices so-named usually were called the justices of the quorum. Meaning "fixed number of members whose presence is necessary to transact business" is first recorded 1610s.