In demonology, Foras’ or Forrasis) is a powerful President of Hell, being obeyed by twenty-nine legions of demons. He teaches logic and ethics in all their branches, the virtues of all herbs and precious stones, can make a man witty, eloquent, invisible (invincible according to some authors), and live long, and can discover treasures and recover lost things.
He is depicted as a strong man.
The Thirty-first Spirit is Foras. He is a Mighty President, and appeareth in the Form of a Strong Man in Human Shape. He can give the understanding to Men how they may know the Virtues of all Herbs and Precious Stones. He teacheth the Arts of Logic and Ethics in all their parts. If desired he maketh men invisible, and to live long, and to be eloquent. He can discover Treasures and recover things Lost. He ruleth over 29 Legions of Spirits, and his Seal is this, which wear thou, etc.S. L. MacGregor Mathers (1904)
His name seems to derive from Latin foras (out, outside).