Emily Dickinson Lexicon

ME-RID'IAN, n. [Fr. meridien; It. meridiano; L. meridies. Qn. Ir. mir, a part; Gr. μειρω, to divide. Varro testifies that this word was originally medidies, (mid-day,) and that he had seen it so written on a sun-dial.]

1. In astronomy and geography, a great circle supposed to be drawn or to pass through the poles of the earth, and the zenith and nadir of any given place, intersecting the equator at right angles, and dividing the hemisphere into eastern and western. Every place on the globe has its meridian, and when the sun arrives at this circle, it is mid-day or noon, whence the name. This circle may be considered to be drawn on the surface of the earth, or it may be considered as a circle in the heavens coinciding with that on the earth.
2. Mid-day; noon.
3. The highest point; as, the meridian of life; the meridian of power or of glory.
4. The particular place or state, with regard to local circumstances or things that distinguish it from others. We say, a book is adapted to the meridian of France or Italy; a measure is adapted to the meridian of London or Washington. Magnetic meridian, a great circle, parallel with the direction of the magnetic needle, and passing through its poles.