Ma'anar ƙamus na kalmar "alkali mai layi" shine mutumin da ke da alhakin tantance ko ball ya sauka a ciki ko a waje da iyakokin filin wasa, musamman a wasanni kamar wasan tennis ko wasan kwallon raga. Alkalin layi yana sanya shi a gefen layi ko ƙarshen layi na filin wasa, kuma babban aikin su shine yin kira daidai akan ko ƙwallon yana ciki ko baya da iyaka. Yawancin lokaci suna aiki tare da wasu jami'ai don tabbatar da cewa an buga wasan cikin adalci kuma bisa ka'ida.