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.
To abandon, especially an unwanted baby in the wilderness.
To reveal, uncover, make visible, bring to light, introduce (to).
To subject photographic film to light thereby recording an image.
To do an activity without protection or intermediary.
To have sex without a condom; to bareback.
Without a condom; bareback.