The Hindu Kush is an 800-kilometre-long (500 mi) mountain range in Central and South Asia to the west of the Himalayas. It stretches from central and eastern Afghanistan into northwestern Pakistan and far southeastern Tajikistan. The range forms the western section of the Hindu Kush Himalayan Region (HKH); to the north, near its northeastern end, the Hindu Kush buttresses the Pamir Mountains to the north near the point where the borders of China, Pakistan and Afghanistan meet, after which it runs southwest through Pakistan and into Afghanistan near their border.

The eastern end of the Hindu Kush merges with the Karakoram Range. Towards its southern end, it connects with the White Mountains near the Kabul River. It divides the valley of the Amu Darya (the ancient Oxus) to the north from the Indus River valley to the south. The range has numerous high snow-capped peaks, with the highest point being Tirich Mir or Terichmir at 7,708 metres (25,289 ft) in the Chitral District of Khyber Pakhtunkhwa, Pakistan.

The Hindu Kush range region was a historically significant center of Buddhism, with sites such as the Bamiyan Buddhas. The range and communities settled in it hosted ancient monasteries, important trade networks and travelers between Central Asia and South Asia. While the vast majority of the region has been majority-Muslim for several centuries now, certain portions of the Hindu Kush only became Islamized relatively recently, such as Kafiristan, which retained ancient polytheistic beliefs until the 19th century when it was converted to Islam by the Emirate of Afghanistan and renamed Nuristan ("land of light"). The Hindu Kush range has also been the passageway for invasions of the Indian subcontinent, and continues to be important to contemporary warfare in Afghanistan.

From a historical perspective, the name Hindu Kush (also written as Hindukush) is relatively recent. It does not appear in the writings of the early Arab geographers and is first mentioned in the works of Ibn Battuta, in the 14th century.

Hindu Kush is generally translated as "Killer of Hindus" or "Hindu-Killer" in the popular literature. The earliest explanation offered for the name comes from Ibn Battuta. According to him, Hindu Kush means Hindu-slayer as slaves from India died in the harsh climatic conditions of the mountains while being taken to Turkestan by traders.

Several other scholars believe the name to be a corruption of Hindu Koh ('mountains of India'). The 16th-century Mughal court historian Abu al-Fazl ibn Mubarak also refers to the range as Hindu Koh in his Ain-i-Akbari. According to Nigel Allan, the term Hindu Kush had two alternate meanings popular for centuries i.e 'mountains of India' and 'sparkling snows of India', with Kush respectively being a soft variant of kuh ('mountain') or referring to the quality of snow. Allan further states that to the Arab geographers Hindu Kush was the frontier boundary of Hindustan.

Another theory posits the name to may have been derived from ancient Avestan, meaning 'water mountain', with Kush probably being a corruption of the Persian word kuh ('mountain'). According to Hobson-Jobson, a 19th-century British dictionary, Hindukush might be a corruption of the ancient Latin Indicus [Caucasus] ('Caucasus of India'); the entry mentions the interpretation first given by Ibn Battuta as a popular theory already at that time, despite doubts cast upon it.

Some 19th-century encyclopedias and gazetteers state the term Hindu Kush to originally have applied only to the peak in the area of the Kushan Pass, which had become a center of the Kushan Empire by the first century.