Astrology is a group of systems, traditions, and beliefs in which knowledge of the relative positions of celestial bodies and related details is held to be useful in understanding, interpreting, and organizing information about personality, human affairs, and other terrestrial matters. A practitioner of astrology is called an astrologer, or, less often, an astrologist.
[Mrs. O reads her horoscope.] Mrs. O: You have green, scaly skin, and a soft yellow underbelly with a series of fin-like ridges running down your spine and tail. Although lizardlike in shape, you can grow anything up to thirty feet in length with huge teeth that can bite off great rocks and trees. You inhabit arid, subtropical zones, and you wear spectacles. Mrs. Trepidatious: It's very good about the spectacles. Mrs. O: It's amazing!
Amusingly, it falls foul of our modern taboo against lazy stereotyping. How would we react if a newspaper published a daily columm that read something like this: "Germans: It is in your nature to be hard-working and methodical, which should serve you well at work today. In your personal relationships, especially this evening, you will need to curb your natural tendency to obey orders. Chinese: Inscrutability has many advantages, but it may be your undoing today. British: Your stiff upper lip may serve you well in business dealings, but try to relax and let yourself go in your social life.
Penny: I'm a Sagittarius, which probably tells you way more than you need to know.
Sheldon: Yes... it tells us that you participate in the mass cultural delusion that the sun's apparent position relative to arbitrarily defined constellations at the time of your birth somehow affects your personality.