(cryptography, informal) Abbreviation of Triple DES, a cipher formed from the Data Encryption Standard (DES) cipher by using it three times.

(physics) The only stable isotope of phosphorus, ³¹₁₅P, having fifteen protons and sixteen neutrons

(physics) The minor stable isotope of chlorine, ³⁷₁₇Cl, having seventeen protons and twenty neutrons; it amounts to about 24% of the element in nature

(physics) The major stable isotope of sulfur, ³²₁₆S, having sixteen protons and sixteen neutrons; it amounts to 95% of the element in nature

(physics) The major stable isotope of chlorine, ³⁵₁₇Cl, having seventeen protons and eighteen neutrons; it amounts to about 76% of the element in nature

(physics) A minor stable isotope of sulfur, ³⁴₁₆S, having sixteen protons and eighteen neutrons; it amounts to about 4% of the element in nature

(physics) A radioactive isotope of sulfur, ³⁵₁₆S, having sixteen protons and nineteen neutrons, and a half-life of about 87 days; it is used as a tracer

(physics) A minor stable isotope of sulfur, ³³₁₆S, having sixteen protons and seventeen neutrons; it amounts to less than 1% of the element in nature

(physics) A long-lived radioactive isotope of chlorine, ³⁶₁₇Cl, having seventeen protons and nineteen neutrons, and a half-life of 3x10⁵ years; it can be used to date samples of groundwater

(physics) A minor stable isotope of sulfur, ³⁶₁₆S, having sixteen protons and twenty neutrons; it amounts to only 0.01% of the element in nature