To reveal, uncover, make visible, bring to light, introduce to.
To subject photographic film to light thereby recording an image.
To abandon, especially an unwanted baby in the wilderness.
To submit to an active (mostly dangerous) substance like an allergen, ozone, nicotine, solvent, or to any other stress, in order to test the reaction, resistance, etc.
To make available to other parts of a program, or to other programs.