A1noun
نَارٌ
nār
fire / hellfire
Example
وَاتَّقُوا النَّارَ الَّتِي أُعِدَّتْ لِلْكَافِرِينَ
wattaqū an-nāra allatī uʿiddat lil-kāfirīn
And fear the Fire which has been prepared for the disbelievers (3:131)
Grammar
Feminine noun (no tāʾ marbūṭa but grammatically feminine). Interestingly shares the root ن-و-ر with نُورٌ (light). Appears over 140 times in the Quran.
Culture
Descriptions of the Fire serve as warnings in the Quran. Islamic scholars emphasize that God's mercy precedes His wrath, and hope should accompany fear.