English, from Hebrew Hanna/Hannah, "favoured one". ONC suggests that the primary spelling should be Anne.

Ann is also a Jewish diminutive for Hanna/Hannah.

A private communication [LG] records Agnes being used in formal records for someone whose birth registration [1830, Catholic] was Ann. This may be a special case for a given family but the fact that such records occur should be noted and considered when searching.

Another correspondent [CMcB] has noted a baptismal Agnes shown as Ann in official records in Kincardineshire, Scotland. There is no general suggestion that the two names are fully interchangeable so we have classified them as lesser synonyms.

The Clan MacLean website suggests that Una is the Gaelic equivalent of Ann but this is not suported by other sources.