ESO Astronomical Glossary - Z
The zenith is the point in the sky directly above the observer. More precisely, it is the point on the sky with an altitude of +90 degrees.
The zodiac is the region of the sky along which the Sun, Moon and planets move, as well as a sequence of 12 constellations It coincides with the plane of the Earth's orbit around the Sun. The constellations in the zodiac are: Capricorn (The Goat), Aquarius (The Water Bearer), Pisces (The Fish), Aries (The Ram), Taurus (The Bull), Gemini (The Twins), Cancer (The Crab), Leo (The Lion), Virgo (The Virgin), Libra (The Balance), Scorpio (The Scorpion), and Sagittarius (The Archer).