SPF

abbreviation for

1. sun protection factor: the effectiveness of a sunscreen in protecting the skin from the sun's ultraviolet UVB radiation, as rated on a scale of increasing protectiveness, the number being the ratio of the radiation dose needed to produce minimal redness when using sunscreen compared to the dose needed to produce the same redness without sunscreen:

   An SPF of 15 will allow you to stay in the sun 15 times longer.

SPF

¹

abbreviation for

1. sender policy framework: a mechanism designed to prevent an e-mail address being duplicated and used as a false address from which to send unsolicited e-mails
2. sun protection factor: an indicator of how effectively a sun cream, lotion, cosmetic, etc, protects the skin from the harmful rays of the sun

   SPF 25

S.P.F.

²

abbreviation for

1. vet science specific pathogen free; denoting animals specially bred to ensure that they are free of specified diseases