Why was the word "وفات -Death" used for the Martyrdom of Hazrat Zahra in the Past?

The literal meaning of "death" covers "any kind of death" and there is no problem in the literal sense of applying death to a martyr.[1] It is God who takes the lives when they die."[2] Therefore, from the Qur'anic point of view, the title of death can be used for a martyr and it does not conflict with martyrdom.

Jafar ibn Abi Talib and Hamzah, the uncle of the Prophet, are among the people who Shia and Sunni agree that they are martyrs, and at the same time, the word "death" is used about them in the hadiths.

Ayesha says:

 "When they brought the news of Jafar's death, we saw sadness on the Prophet's face."[3]

Asmi Makki Shafi'i has used the word "death" about Hamza Sayyid al-Shahada: "After the death of Hamza bin Abd al-Muttalib and the Messenger of God."[4]

There are narrations that state that Hazrat Zahra was martyred.

It was narrated from Ali bin Jafar that his brother Imam Kazim (peace be upon him) said:

 "Verily, Fatima is a righteous martyr."[5]

References:

[1] Lasan al-Arab, vol. 3, p. 960; Omid Persian dictionary and Dehkhoda dictionary under the word death.

[2]  Surah Zammar, verse 42. اللهُ یتَوَفّی الْاَنْفُسَ حِینَ مَوْتِها

[3]  Kitab al-Musnaf fi al-Ahadith and al-Athar, vol. 3, p. 62.       عن عَائِشَةَ قالت لَمَّا أَتَتْ وَفَاةُ جَعْفَرٍ عَرَفْنَا في وَجْهِ رسول اللهِ صلي الله عليه وسلم الْحُزْنَ

[4] Samat al-Nujum al-Awali in Anba' al-Awael and Tawali, vol. 1, p. 426.

[5] Al-Kafi, vol. 1, p. 458.  «عَنْ عَلِی بْنِ جَعْفَرٍ عَنْ أخِیهِ أبِی الْحَسَنِ علیه‌السّلام: قالَ:إنَّ فاطِمَهَ صِدِّیقَهٌ شَهِیدَه