Of disputed origin. It has been in use since the 17th century. It is now generally taken as a feminine equivalent of Andreas, and this probably represents its actual origin. However, it was not in use in the Middle Ages, and the suggestion has also been made that it represents a coinage in English from the Greek vocabulary word andreia ‘manliness, virility’.
English: from Middle English more ‘moor’, ‘marsh’, ‘fen’, ‘area of uncultivated land’ (Old English mōr), hence a topographic name for someone who lived in such a place or a habitational name from any of the various places named with this word, as for example Moore in Cheshire or More in Shropshire.