1660s, nativized from French limonade (17c.), which is from Italian limonata or else a French formation from limon; see lemon (n.1) + -ade. The earlier English spelling was lemonado (c. 1640) with false Spanish ending.
lemma
lemming
lemniscus
Lemnos
lemon
lemonade
lemony
lemur
Lemuria
Lena
Lenape