A heresy begun by Apollinaris the Younger, Bishop
of Laodicea, c.376, teaching that Christ had a human sensitive soul, but had
no human rational mind, the place of which was taken by Divine Logos. It was
condemned by Roman Councils, 377 and 381, and the Council of Constantinople,
381. The sect perished about 416, some members returning to the Church,
while the rest became Monophysites, believing that Christ had only a divine,
but no human, will.
New Catholic Dictionary