1 (geometry) A polyhedron with parallel ends of the same size and shape, the other faces being parallelogram-shaped sides.  A transparent block in the shape of a prism (typically with triangular ends), used to split or reflect light.
To the Jews, solar eclipses meant that the moon was passing between the sun and the earth, thereby blocking the suns light. Notwithstanding the physical explanation of a solar eclipse, there is also spiritual significance to it: At the time when the sun is eclipsed, it is an unfavorable period for the world. A parable: This can be compared to a human king who made a feast for his subjects, and placed a lantern before them.
Solar Eclipses are very meaningful New Moons. That makes them spiked times of change -- both within and without. Since the Sun and Moon are in the same Zodiac sign, the energies of that sign are supersized. It's a concentration that can greatly impact you, if it glances off a significant point in your chart.