Noah Webster's New International Dictionary of the English Language

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.