1. I-adjective (keiyoushi)

   blue; azure

   なぜ空が青いか知っているか。

2. green

   mostly archaic or in ref. to fruits, vegetables and traffic lights

3. pale (facial color); gray; grey

4. unripe; inexperienced

Also written 蒼い【あおい】aoi、碧い【あおい】aoi