below the eyes; under the eyes
Refers to the area directly beneath the eyes, often used when describing dark circles, bags, or something positioned there.
Lately, I'm bothered by the dark circles under my eyes.
length from eyes to tail fin (of a fish)
Specialized term used in fishing or ichthyology to measure the distance from the eye to the base of the tail fin.
This fish has a long distance from the eyes to the tail fin and a low body depth.
Compound of 目 (eye) + の (possessive particle) + 下 (below). The literal meaning 'below the eyes' is extended to a specific measurement in fish.