The name Shannon originated in Ireland and is directly linked to the River Shannon, the island's longest river. The name is a combination of Irish sean "old, wise" and abhainn "river". Shannon is now used as a first name for both males and females. A common misconception is that the word Shannon means wise when in fact it is really named after the river.
The name Shannon was once only a masculine name. The popularity of the name Shannon as a boy's name slowly declined as the 20th century brought more liking to naming girls Shannon instead of only boys. This trend started between the 1960's and the 1990's. Parents began to lose interest in naming their sons Shannon, and began naming their daughters Shannon instead. Other forms of Shannon are Shanan, Shanen, Shannan, Shannen and Shanon.