4. (Science: botany) a species of crowfoot.
5. The aurora borealis or aurora australis (northern or southern lights). Aurora borealis, i. E, northern daybreak; popularly called northern lights. A luminous meteoric phenomenon, visible only at night, and supposed to be of electrical origin. This species of light usually appears in streams, ascending toward the zenith from a dusky line or bank, a few degrees above the northern horizon; when reaching south beyond the zenith, it forms what is called the corona, about a spot in the heavens toward which the dipping needle points. Occasionally the aurora appears as an arch of light across the heavens from east to west. Sometimes it assumes a wavy appearance, and the streams of light are then called merry dancers. They assume a variety of colours, from a pale red or yellow to a deep red or blood colour. The aurora australis is a corresponding phenomenon in the southern hemisphere, the streams of light ascending in the same manner from near the southern horizon.