From the Greek word melissa ‘honey bee’. It is the name of the good witch who releases Rogero from the power of the bad witch Alcina in Ariosto's narrative poem Orlando Furioso (1532). The name was fairly popular in the 1990s, along with other girls’ names sharing the same first syllable.
English and Scottish: patronymic from the medieval personal name Nel or Neal, Anglo-Scandinavian forms of the Gaelic name Niall (see Neill). This was adopted by the Scandinavians in the form Njal and was introduced into northern England and East Anglia by them, rather than being taken directly from Gaelic.