The keyword term "september 11th zodiac animal" is a noun phrase. It functions as a single conceptual unit referring to a specific topic. This topic, however, arises from a common conflation of two different astrological systems, as no primary zodiac tradition assigns a specific animal to a single calendar day.
The Western (or tropical) zodiac assigns astrological signs based on specific date ranges within the year. A birth date of September 11th falls under the sign of Virgo. The symbol for Virgo is the Virgin or the Maiden, not an animal. In contrast, the Chinese zodiac assigns one of twelve animals based on a 12-year cycle. The determining factor for the Chinese zodiac animal is the birth year, not the month or day. For instance, a person born on September 11, 1980, is a Monkey, while a person born on September 11, 1981, is a Rooster.
To determine an individual's associated astrological symbol, it is necessary to specify the system being referenced. If using the Western zodiac, the sign for this date is Virgo. If using the Chinese zodiac, the birth year is required to identify the correct animal sign. The concept of an animal sign for a specific day like September 11th does not exist as a standalone principle in either system.
