"St.
Gabriel is the Angel of the Annunciation. It was through him that the
compliments of the Holy Trinity were addressed to Mary; that the mystery
of the Trinity was first stated to man; that the Incarnation was announced;
that the Immaculate Conception was declared; that the first notes of
the Rosary were struck."
(Handbook; 24, 5)
The name Gabriel means "man of God," or "God has shown himself mighty." It appears first in the prophesies of Daniel in the Old Testament. The angel announced to Daniel the prophecy of the seventy weeks. His name also occurs in the apocryphal book of Henoch. He was the angel who appeared to Zachariah to announce the birth of St. John the Baptizer.
St. Gabriel is the patron of communications workers. The feast day is September 29th.
Pope Saint Gregory the Great:
"You should be aware that the word "angel" denotes a function rather than a nature. Those holy spirits of heaven have indeed always been spirits. They can only be called angels when they deliver some message. Moreover, those who deliver messages of lesser importance are called angels; and those who proclaim messages of supreme importance are called archangels.
And so it was that not merely an angel but the archangel Gabriel was
sent to the Virgin Mary. It was only fitting that the highest angel should
come to announce the greatest of all messages.... So too Gabriel, who
is called God's strength, was sent to Mary. He came to announce the One
who appeared as a humble man to quell the cosmic powers. Thus God's strength
announced the coming of the Lord of the heavenly powers, mighty in battle."