1. Pertaining to the doctrines or tenets of Sabellius. See Sabellian, n.
2. an extinct Osco-Umbrian language of ancient Italy that survives only in a few inscriptions
3. A follower of Sabellius, a presbyter of Ptolemais in the third century, who maintained that there is but one person in the Godhead, and that the Son and Holy Spirit are only different powers, operations, or offices of the one God the Father.