The term 'bluish-green' can be described by four different words, all of which have four letters: aqua, CYAN, TEAL, and nile. Aqua is a light blue-green color that is often associated with the ocean or water. CYAN is a slightly darker shade of blue-green, and is often used to describe the color of the sky. TEAL is a deep blue-green color, and is often used to describe the color of certain birds. Nile is a very dark blue-green color, and is named after the river in Egypt. All of these colors are variations of the same hue, and together they can be used to describe the term 'bluish-green'.