- Antiphons general definition
Anti- in return, phonos phone – voice, to speak, to say Gk, Latin derivation
The short answer is that an antiphon is another psalm (sacred song or poem not necessarily from the book of Psalms) that is selected for that specific day to go along with the readings for the Mass of the day. It is a tool, given to us in sacred scripture, that helps us to better understand the readings for that Mass.
Antiphons are sung, helps to remain in the brain. Introit, Church as a gentle mother, repeat the verse, gentle way of instruction. Sung to as a learning. Ponder on the melody later on.
These texts are arranged into verses and refrains, just like the Responsorial Psalm, but they are referred to as “antiphons” because traditionally, they were sung by multiple choirs. Usually, one choir would be at the front of the church and sing the refrain, while another choir would be in the rear and chant the verses, creating a back and forth “call and response” or “antiphonal” effect. The antiphons were adopted from Hebrew worship and were introduced into Western civilization by St. Ambrose in the 4th Century.
Beauty of internet, all of these accessible. Find words, musical notation. Easy to sing. For the everywoman. Key generally accessible to most. Melodies intuitive. Plain chant. Simple. Gregorian chant beautiful. Feed yourself with beautiful music.
III. Definition of Greater Advent Antiphon, The O Antiphons have been chanted in the Church since at least the 8th century. There are many levels to the symbolism and foreshadowing of the antiphons. Individually, they each speak on their own, addressing our Lord by a different title or name given to him in Old Testament prophecies, imploring him to come and save his people. These antiphons are called the “O Antiphons” because each chant begins with great cry, “O …” :
 https://aleteia.org/2019/12/16/the-great-o-antiphons-an-advent-tradition/ accessed November 8, 2021