Organizations

• Air Tahiti Nui, a French Polynesian airline with the IATA airline designation "TN"
• Texas and Northern Railway, an American Railway with the AAR reporting mark "TN"

Places

• Tamil Nadu, a state in southern India, whose ISO abbreviation is "IN-TN"
• Tennessee, a state in the United States, whose postal abbreviation is "TN"
• Tonbridge, a region in England with the postcode "TN"
• Tunisia, a country in Africa, whose ISO country code is "TN"
• The province of Trento, a province in Italy, whose ISO abbreviation is "IT-TN"

Scientific terms

• Neel Temperature, the temperature at which an antiferromagnetic material becomes paramagnetic (represented as T_N)
• Trigeminal neuralgia, a neuropathic disorder
• Transposon (when immediately followed by a number), a DNA sequence that can change positions
• Twisted Nematic, an LCD panel technology