Triglav (ˈtɾiːɡlau̯; Terglau; Tricorno), with an elevation of , is the highest mountain in Slovenia and the highest peak of the Julian Alps. The mountain is the pre-eminent symbol of the Slovene nation. It is the centrepiece of Triglav National Park, Slovenia's only national park. Triglav was also the highest peak in Yugoslavia before Slovenia's independence in 1991.
Various names have been used for the mountain through history. An old map from 1567 named it Ocra mons, whereas Johann Weikhard von Valvasor named it Krma in the second half of the 17th century. According to the German mountaineer and professor Adolf Gstirner, the name Triglav first appeared in written sources as Terglau in 1452, but the original source has been lost. The next known occurrence of Terglau is cited by Gstirner and is from a court description of the border in 1573. Early forms of the name Triglav also include Terglau in 1612, Terglou in 1664 and Terklou around 1778–89. The name is derived from the compound *Tri-golvъ (literally 'three-head'—that is, 'three peaks'), which may be understood literally because the mountain has three peaks when viewed from much of Upper Carniola. It is unlikely that the name has any connection to the Slavic deity Triglav. In the local dialect, the name is pronounced tərˈgwɔu̯ (with a second-syllable accent, as if it was written Trglov, with the dark L experiencing vocalization) in contrast to standard Slovene Tríglav. The highest peak is sometimes also called Big Mount Triglav (Veliki Triglav) to distinguish it from Little Mount Triglav (Mali Triglav, ) immediately to the east.
The first recorded ascent of Triglav was achieved in 1778, at the initiative of the industrialist and polymath Sigmund Zois. According to the most commonly cited report, published in the newspaper Illyrisches Blatt in 1821 by the historian and geographer Johann Richter, these were the surgeon Lovrenz Willomitzer (written as Willonitzer by Richter), the chamois hunter Štefan Rožič, and the miners Luka Korošec and Matevž Kos.