Aquarius (♒) (Greek: Ύδροχόος, "Hudrokhoös", Latin: "Aquārius") is the eleventh astrological sign in the Zodiac, originating from the constellation Aquarius. It spans the Zodiac between the 300th and 329th degree of celestial longitude. In astrology, Aquarius is considered a masculine, positive (extrovert) sign. It is also considered an air sign and is one of four fixed signs. Aquarius has been traditionally ruled by the planet Saturn, and, since its discovery, Uranus has been considered a modern co-ruler of this sign. "Exalting" planets are either Mars and/or Neptune, while the "fall" planets are Mercury and/or Venus.^{[citation needed]}

In Western conceptions of astrology an individual born under this Sun sign is known as an Aquarian. Although the astrological sign of Aquarius may begin as early as January 19 in some years, the Sun typically leaves Capricorn and enters Aquarius on the cusp day January 20th. The Sun is in Aquarius under the tropical zodiac from approximately then to February 17. Under the Sidereal Zodiac, the Sun is in the astrological sign of Aquarius from February 12th to 14th and leaves between March 8th and 10th, depending on leap year. According to Hindu Astrology, which uses the Sidereal Zodiac, one can be an Aquarius at any time of year, as the defining factor of personality is interpreted from the Zodiac sign rising on the Eastern Horizon at the specific time of birth, rather than the astronomical transit of the Sun.

Aquarius may refer to:

Astrology consists of a number of belief systems which hold that there is a relationship between astronomical phenomena and events in the human world. In the West, astrology most often consists of a system of horoscopes that claim to predict aspects of an individual's personality or life history based on the positions of the sun, moon, and other planetary objects at the time of their birth. Many cultures have attached importance to astronomical events, and the Indians, Chinese, and Mayans developed elaborate systems for predicting terrestrial events from celestial observations.

Among Indo-European peoples, astrology has been dated to the third millennium BCE, with roots in calendrical systems used to predict seasonal shifts and to interpret celestial cycles as signs of divine communications. Through most of its history, astrology was considered a scholarly tradition. It was accepted in political and academic contexts, and its concepts were built into other studies, such as astronomy, alchemy, meteorology, and medicine. At the end of the 17th century, new scientific concepts in astronomy (such as heliocentrism) began to damage the credibility of astrology, and subsequent controlled studies failed to confirm its predictive value. Astrology thus lost its academic and theoretical standing. Astrology saw a popular revival in the 19th and 20th centuries as part of a general revival of spiritualism and later New Age philosophy, and through the influence of mass media such as newspaper horoscopes.