a girl, usually around ages 7–17; a young female. Common in literature and reporting; in casual speech people often say '女の子'.
公園で少女が赤い自転車に乗っていた。
A girl was riding a red bicycle in the park.
この漫画は少女向け（少女漫画）だ。
This manga is aimed at girls (shōjo manga).
彼女はまだ少女のように純粋だ。
She is still pure like a young girl.
archaic/historical usage: in certain historical age classifications (e.g., ritsuryō period), it referred to females aged about 17–20; now seen in historical or academic contexts.
律令では少女は十七から二十歳を指したと記録されている。
Records state that under the ritsuryō system, shōjo referred to females aged 17 to 20.