cit·ro·nel·la 
(sĭt′rə-nĕlə)
(sĭt′rə-nĕlə)n.
1. A tropical Asian grass (Cymbopogon nardus) that has bluish-green, lemon-scented leaves and yields an essential oil.
2. A pale yellow to brownish aromatic oil obtained from this plant, used chiefly in perfumery and also in some insect repellents and commercial flavorings.
[New Latin, from French citronnelle, lemon oil, diminutive of citron, citron; see CITRON.]