|The word "Theotokos" is Greek and literally means "God-bearer," although in more general terms it can be taken to mean "Mother of God."
The Fathers of the Church saw in this name, Theotokos, a "compendium of the Church's faith in the Incarnation."
As St Cyril of Alexandria said: "To confess our faith in orthodox fashion ... it is enough to confess that the Blessed Virgin is Theotokos," (Homiliae Diversae 15: PG77. 1093c).
For St John Damascene, "This name expresses the whole mystery of the economy. If she who gave birth is the Mother of God, then He who was born of her is definitely God and also definitely man ... This [name] signifies the one hypostasis and the two natures and the two births of Our Lord Jesus Christ," (De Fide Orthodoxa 3, 12; PG 94. 1029CD).
Source: John Saward, Christ is the Answer, (T & T Clark, Edinburgh, 1995).
Regarding pronunciation, the practice in the West seems to be to pronounce Theotokos as "thee-ott-oh-kos," whereas in the East, "thee-owe-/-toke-oss," seems to be preferred.