(1):

(n.) Drowsy; inclined to, or overcome by, sleep.

(2):

(n.) Tending to induce sleep; soporiferous; somniferous; as, a sleepy drink or potion.

(3):

(n.) Dull; lazy; heavy; sluggish.

(4):

(n.) Characterized by an absence of watchfulness; as, sleepy security.