noun: Initialism of sun protection factor. [An indication of how long a sunscreen remains effective when applied to the skin.]
noun: Initialism of single point of failure. [A component in a device, or a point in a network, that, if it were to fail would cause the entire device or network to fail; normally eliminated by adding redundancy.]
noun: Initialism of spray polyurethane foam.
noun: Initialism of spruce-pine-fir, mixed softwood timber
noun: (Internet) Initialism of Sender Policy Framework.
