A sanitary towel (aka. a sanitary napkin, a feminine napkin, a menstrual pad)) is an absorbent item worn by women in their underwear when menstruating, bleeding after giving birth, recovering from gynecologic surgery, experiencing a miscarriage or abortion, or in any other situation where it is necessary to absorb a flow of blood from the vagina.
Sanitary towel is a common term to hear in the UK.
Hey, that swimming pool float looks like a giant sanitary towel!
A sunburn or suntan focused on the left arm. It is caused by the left side of the body being the only half that gets exposed to sunlight while driving. Presumably, it would be located on the right side of the body in countries where they drive on the left side of the road.