Ida, called the "Brigid of Munster", was born in 480 in the present County Waterford. Her father was Cennfoelad or Confhaola and her mother was Necta. Cennfoelad was descended from Felim the lawgiver.She was baptised as Deirdre and grew up in Drum, County Waterford. Ita was said to embody the six virtues of Irish womanhood – wisdom, purity, musical ability, gentle speech and needle skills. She is also reported to have rejected a prestigious marriage for a life as a consecrated woman religious. At the age of sixteen she moved to Cluain Credhail, a place-name that has ever since been known as Killeedy – meaning "Church of St. Ita" – in County Limerick, where she founded a small community of nuns and resided for the remainder of her life, in community with other consecrated women. Bishop Declan of Ardmore conferred the veil on her. Legend has it that Ita was lead to Killeedy by three heavenly lights. The first was at the top of the Galtee mountains, the second on the Mullaghareirk mountains and the third at Cluain Creadhail, which is nowadays Killeedy. Her sister Fiona also went to Killeedy with her and became a member of the community.

A strongly individualistic character is glimpsed in the stories that surround her life. When she decided to settle in Killeedy, a chieftain offered her a large grant of land to support the convent. But Ita would accept only four acres, which she cultivated intensively.The community group seems to have had a school for little boys where they were taught "Faith in God with purity of heart; simplicity of life with religion; generosity with love".[6] Her pupils are said to have included Saint Brendan, whom Bishop Erc gave to Ita in fosterage when he was a year old. St. Ita kept him until he was six.[5]

The great Navigator visited her between his voyages and always deferred to her counsel. Brendan is believed to have asked her what three things God loved best. "True faith in God and a pure heart, a simple life with a religious spirit and open-handedness inspired by charity," she answered. The three things God most detested were a scowling face, obstinacy in wrongdoing, and too great a confidence in the power of money.

She dedicated herself to prayer, fasting, simplicity and cultivating a gift for spiritual discernment. She was also endowed with the gift of prophecy and was held in great veneration by a large number of contemporary saints, men as well as women. Ita was said to have a gift for guiding people in holiness. She was much sought after as a spiritual director. During this period of Christianity, the Celtic Church was more advanced than other churches at the time in recognising qualities of spiritual leadership in women and in encouraging women in this role. It is thought that Ita may have been abbess of a double monastery of men and women.

Her legend places a great deal of emphasis on her austerity, as told by St. Cuimin of County Down, and numerous miracles are recorded of her. She is also said to be the originator of an Irish lullaby for the infant Jesus, an English version of which was set for voice and piano by the American composer Samuel Barber. She probably died of cancer, though contemporary chroniclers describe how her side was consumed by a beetle that eventually grew to the size of a pig – understandable given the early medieval conflation of sanctity and suffering. When she felt her end approaching she sent for her community of nuns, and invoked the blessing of heaven on the clergy and laity

Prayer to Naomh Ide:

Lord, you, give us food to strengthen us,
And clothes to keep us warm
Help us to follow the example of St. Ita
By praying every day
And by helping others
We ask this through Christ the Lord
Amen