Quick answer
Neasa is a girl name.
Pronunciation: Irish /ˈnʲa.sˠə/.
Meaning and history
From Old Irish Ness, meaning uncertain. In Irish legend she was the mother of Conchobar. She installed her son as king of Ulster by convincing Fergus mac Róich (her husband and Conchobar's stepfather) to give up his throne to the boy for a year and then helping him rule so astutely that the Ulstermen demanded that he remain as king. According to some versions of the legend she was originally named Assa "gentle", but was renamed Ní-assa "not gentle" after she sought to avenge the murders of her foster fathers.
Notes and context
Usage: irish, irish mythology