1. constellation in northern hemisphere: a zodiacal constellation of the northern hemisphere
2. 12th sign of zodiac: the 12th sign of the zodiac, represented by two fishes and lasting from approximately February 19 to March 20. Pisces is classified as a water sign and its ruling planets are Jupiter and Neptune.
3. somebody born under Pisces: somebody whose birthday falls between February 19 and March 20
[Pre-12th century. < Latin, plural of piscis "fish"]