vain / vane / vein [vein]
vain – adj. – 1. conceited; 2, lacking substance or worth
vane – n. – a thin, rigid blade of a fan, propeller, windmill etc. usually moved by air currents
vein – n. – 1. in vertebrates – vessels that transport blood back to the heart; 2. in plants etc. – similar vessels that transport fluid and nutrients; 3. in rocks, etc. – streaks of different composition or colour