"resembling or infused with lemon," 1846, from lemon (n.1) + -y (2). In Australia/New Zealand slang, also "irritated, angry" (1941). An earlier adjective was lemonish (1719).
lemming
lemniscus
Lemnos
lemon
lemonade
lemony
lemur
Lemuria
Lena
Lenape
lend