"writ from a superior court to an inferior court or officer specifying that something be done by the persons addressed, as being within their office or duty," 1530s (late 14c. in Anglo-French), from Latin mandamus "we order" (opening word of the writ), first person plural present indicative of mandare "to order" (see mandate (n.)). "Its use is generally confined to cases of complaint by some person having an interest in the performance of a public duty, when effectual relief against its neglect cannot be had in the course of an ordinary action" [Century Dictionary].
It forms all or part of: amanuensis; command; commando; commend; countermand; demand; Edmund; emancipate; legerdemain; maintain; manacle; manage; manciple; mandamus; mandate; manege; maneuver; manicure; manifest; manipulation; manner; manque; mansuetude; manual; manubrium; manufacture; manumission; manumit; manure; manuscript; mastiff; Maundy Thursday; mortmain; Raymond; recommend; remand; Sigismund.
It is the hypothetical source of/evidence for its existence is provided by: Hittite maniiahh- "to distribute, entrust;" Greek mane "hand," Latin manus "hand, strength, power over; armed force; handwriting," mandare "to order, commit to one's charge," literally "to give into one's hand;" Old Norse mund "hand," Old English mund "hand, protection, guardian," German Vormund "guardian;" Old Irish muin "protection, patronage."