Elder
Scottish and English: distinguishing nickname bestowed on the elder (Old English ealdra) of two bearers of the same personal name. It may also denote an elder of a Church, in the sense of a senior and respected member of a congregation.
Americanized form of German Elter, which has the same meaning as 1.
Dictionary of American Family Names, Oxford University Press, ISBN 0-19-508137-4
Elter
German: distinguishing nickname bestowed on the elder (Middle High German elter) of two bearers of the same personal name. In North America, this surname has frequently been assimilated to English and Scottish Elder.
Dictionary of American Family Names, Oxford University Press, ISBN 0-19-508137-4