BOH-an
Goddess of the River Boyne and mother of Aengus by the Dagda.
Boann gives her name to the River Boyne, and the Dindsenchas (the medieval lore explaining Irish place-names) tells how the river came to be: she defies a taboo by walking around a forbidden well, which rises up and chases her to the sea, becoming the Boyne in the process.
Her affair with the Dagda produces Aengus — conceived and born, by trick of the Dagda's magic, within a single day, so that Boann's husband Elcmar never learns of it. That same trick is what later lets Aengus claim Newgrange, in the Boyne valley Boann herself is named for.