To change to a tan colour due to exposure to the sun.
No matter how long I stay out in the sun, I never tan. though I do burn.
To change an animal hide into leather by soaking it in tannic acid. To work as a tanner.
To spank or beat.
Having a suntan.
You're looking very tanned.
(of leather) Finished, made using tannic acid (as opposed to abrasion).