- a substance, as para-aminobenzoic acid, used in lotions, cosmetics, etc. to block certain ultraviolet rays of the sun and reduce the danger of sunburn; sunscreen
- a lotion, cosmetic, etc. containing this
See sunblock in American Heritage Dictionary 4
also sun block noun
A preparation that prevents sunburn by filtering out the sun's ultraviolet rays, often purported to offer more protection than a sunscreen.
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