French, from an old Provençal name meaning "foreign", introduced into Britain by Eleanor of Aquitane [1122-1204], on her marriage to Henry II, King of England.
There is a possibility that Eleanor was derived from or a variant of Helen. Also it may be recorded as Helenore, of which there were a few records in the 1841 Census of Aberdeenshire, or as one of the other spelling variants shown, above.
Alianora was used as a Latinised version of Eleanor/Eleanora in many old documents. Search for Alianor* to take account of Latin case endings.