Margaret f. Greek μαργαρίτης 'pearl'.
The name of a number of saints, including a perhaps apocryphal 5th C saint, an 11th C queen of Scotland, a 12th C Hungarian nun, a 13th C Hungarian, a 13th C Italian, a 14th C Italian, a 15th C Italian, and two 16th C Englishwomen; the name of a 13th C Empress consort of Byzantium, a 13th C queen consort of France, a 13th C queen of Scotland, 14th-15th C queen of Denmark, a 15th C queen consort of England, a 16th C queen consort of Scotland, a 16th C queen of Navarre, and a 16th C queen of France.
The popularity of Margaret the Virgin-Martyr was a strong cause of this name's enduring popularity in the Middle Ages, particularly in France and England, though the name was rare, in any culture, before the 12th C. The French form, Marguerite, became Margery (and variants) in Middle English. Margaret and Margery were often considered distinct names from as early as the 13th century, but even in the 16th century there is evidence for the same person being recorded by both variants, showing that the connection was still recognized. For more information see Withycombe s.n. Margery.
The English diminutives Mag, Magot, Meg, Meggot, Megot and the vernacular forms Margery, Mariory, and Mergeret are witnessed in 1379 in the relational bynames Magsoñ (WRYPT1 p. 38), Magotsoñ (WRYPT1 p. 149), Megsoñ (WRYPT1 p. 38), Meggotsoñ (WRYPT1 p. 26), Megotsoñ (WRYPT1 p. 9), Margerysoñ (WRYPT1 p. 11), Mariorymaydeñ WRYPT1 p. 306), and Mergeretdoghter (WRYPT1 p. 30).