What word is a half circle?

Which word means halfway between bitter and sweet?

Which prefix means 'half'?

Which word means halfway awake and halfway asleep?

Which word means it occurs twice a year or happens every half year?

Which word means one half of the earth as divided by the equator or prime meridian?

Which word is relating to a halfway dry region: having little annual rainfall?

What word means halfway between casual and formal attire or dress?