Airmid was a healing goddess of the Tuatha De Danann order. She was the goddess of medicinal plants and keeper of the spring. She can regenerate.
Airmid is the daughter of Dianecht. She and Miach helped Nuada when his arm was cut off in the Fir Bolgs invasion during the Great War. Miach reattached Nuada's regenerated arm back to his body with his amazing surgical skills.
Airmid, Miach, and Dianecht built the Well of Slaine in Ireland. The Well of Slaine was also referred to as the Well of Health. They casted spells over it, so that the water could restore life and put the warriors back in perfect health. During the second war, Battle of Moytura,things got bad for the Tuatha De Danann. The enemies filled the well with stones . Later, the well was known as the Heapstown Cairn.
Dianecht became jealous of his son for his gifts in healing and medicine, that he cut Miach in a number of places. Each time Miach healed himself, his father got more and more angry each time. Dianecht lost all control and struck Miach in the head severing his brain from inside of his body killing him. Airmid buried her brother with so much sorrow. When she went to visit his grave one day,there were herbs for covering Miach's grave for every body part. Miach taught Airmid well.
Airmid started gathering the herbs, when she did they talked to her, telling her what they can be used for. She arranged them systematically in her cloak according to their uses and properties. With the knowledge she gained from them, she used them to heal people.
Dianecht's obsessive hatred for Miach did not end with his death. Dianecht overturned Airmid's cloak, letting the herbs fly away in the wind. He made sure Airmid was the only one who had the knowledge of the herbs, not wanting anyone to gain the immortality the herbs had to offer.
Airmid could not stand her father. She couldn't stand being around him, so she left to go to a place where he would never be. It is said she is a physician in the mountains, healing fairies, elves, and humans back to good health using the knowledge she has gained.
Airmid: Celtic Mythology