Agnessa’s name day is January 21, the feast of Agnes of Rome.
Churches that follow the Old (Julian) Calendar keep the same feast on February 3 of the civil calendar. See everything commemorated on January 21.
The saint behind the name
Agnes of Rome
January 21, Holy Woman, Αγνή
St. Agnes was a young girl of Rome who, refusing marriage for love of Christ, was denounced as a Christian in the persecution of the early fourth century. Tradition relates that she was sent to a brothel and preserved unharmed by God before being put to death by the sword at the age of about thirteen.
Also celebrating on January 21
These names share the feast, many of them other forms of the same name:
What to say on a name day
The Greek wish is Χρόνια Πολλά (Chronia Polla), “many years.” A call or a short message on the day is what people remember. See name day wishes you can send and what a name day is.