Nectarine tree, persica lezvis, is a variety of peach, known for its smooth rind and its sweet taste. There’s a general belief that the word nectarine comes from the word nectar, a fabled saccharine drink of the ancient Greek gods with a pleasant taste.
This is quite strange, as nectarines imported in Greece at a later time and they called apple peaches, while the word nectarine is met for the first time in the English dictionary in 1616. There is another given etymology, not so known and common, that the word nectarine comes from a Persian word NEC that means the best because nectarine is thought to be the finest kind of peach. So, those who imported it first from the East retained its native Persian name.
References
Cooley Arnold James, Dictionary of the English Language Exhibiting Orthography,
Pronunciation and Definition of Words, W.&R. Chambers, 1861.
H. Fox Talbot, English Etymologies, John Murray, 1847.
Carcione Joe, The New Greengrocer Cook, Pete Carcione, 2010.