Meridian

Part of speech: noun (n.)

1. Midday; noon.

2. Hence: The highest point, as of success, prosperity, or the like; culmination. I have touched the highest point of all my greatness, And from that full meridian of my glory I haste now to my setting. Shak.

3. A great circle of the sphere passing through the poles of the heavens and the zenith of a given place. It is crossed by the sun at midday.

4. A great circle on the surface of the earth, passing through the poles and any given place; also, the half of such a circle included between the poles.

Part of speech: adjective (a.)

1. Being at, or pertaining to, midday; belonging to, or passing through, the highest point attained by the sun in his diurnal course. "Meridian hour." Milton. Tables ... to find the altitude meridian. Chaucer.

2. Pertaining to the highest point or culmination; as, meridian splendor.