The Year of Sorrow (Arabic: عام الحزن, romanized 'Ām al-Ḥuzn, "Year of Sadness") names the tenth year of Muhammad's prophethood (c. 619 CE), in which his wife Khadijah and his uncle and protector Abu Talib both died.
After Abu Talib's death, Muhammad lost his clan's protection and became vulnerable; he subsequently sought support in Ta'if and eventually secured protection from Mut'im ibn 'Adi of the Banu Nawfal clan to return safely to Mecca.
This article itself does not discuss the word ḥuzn linguistically or state how many times it (or its root) appears in the Qur'an — it uses the term only as the traditional name of this historical year, not as a lexicographic subject.
Gaps
No etymological or Qur'anic-occurrence-count content — see the word page's recorded disagreement between two secondhand, unverified counts found elsewhere.