English from Hebrew "appointed by God"; OT Book of Jeremiah. Popular with Puritans.
This forename occurs rarely in the 1841 Census of Aberdeenshire together with very rare occurrences of Jerem [which could be Jeremy] and Jeremia.
In old documents in Latin, the forms Hierimias or Jeremias may be used, with appropriate case endings.
In Scotland Diarmad and in Ireland Diarmaid [and their variants] may be Anglicized as Jeremiah. Correspondents [Jf and GGF] have noted Irish parish records where the Gaelic Diarmaid has been used fully synonymously with Jeremiah.