noun Date: 1978 a number assigned to a sunscreen that is the factor by which the time required for unprotected skin to become sunburned is increased when the sunscreen is used
SUN PROTECTION FACTOR
Meaning of SUN PROTECTION FACTOR in English
Merriam Webster. Explanatory English dictionary Merriam Webster. Толковый словарь английского языка Мерриам-Уэбстер. 2012