1. English short form of, and now more popular as a given name than, Amabel, from Old French "friendly, amiable".
Although Mabel appeared as early as the 12th century, it occurred very rarely in the 1841 Census of Aberdeenshire.
Amabilia was a Latinised version of Mabel/Amabel, used in old documents. Search on Amabili* to allow for Latin endings.
2. Spanish elision of Maria and Isabel.