marked or discoloured with something that is not easily removed

a stained beer mat

her ink-stained fingers

(of a material or object) coloured by application of a penetrative dye or chemical

stained timber floorboards

a dark brown stained wood

mark or discolour with something that is not easily removed

her clothing was stained with blood

red powder paint can stain

colour (a material or object) by applying a penetrative dye or chemical

wood can always be stained to a darker shade