إحياء · iḥyāʾ · reviving, bringing back to life

• Met in: V1 p1 ¶2: «...من تحرير كتاب في إحياء علوم الدين...»
• Dictionary form: إِحْيَاء, the verbal noun (maṣdar) of the verb أَحْيَا, "he gave life, revived" (corpus lemma أَحْيَا, 51 times in the Quran)
• Pattern: إِفْعَال (ifʿāl), the verbal noun of Form IV (أَفْعَلَ). Form IV often means "to make something so": حَيِيَ, to live, becomes أَحْيَا, to make live.
• Meaning here: The reviving of the sciences of the religion: bringing back to life a knowledge that has died among people (p2).

Ibn Faris, Maqāyīs al-Lugha, root حيي, vol 2, p 121

الحاء والياء والحرف المعتل أصلان: أحدهما خلاف الموت، والآخر الاستحياء الذي [هو] ضد الوقاحة

Two origins: one is the opposite of death (life); the other is shyness (istiḥyāʾ), the opposite of shamelessness. So ḥayāʾ, modesty, is from the same root as ḥayāt, life.

Urdu bridge

احیاء is used in Urdu (احیائے دین, reviving the religion), and حیات (life) and حیا (modesty) are everyday Urdu. (to be confirmed)

Quran

184 words from this root (Quranic Arabic Corpus). Most common: حَيَوٰة (life) ×76, أَحْيَا (gave life) ×51, حَيّ (living) ×24.

فَٱنظُرْ إِلَىٰٓ ءَاثَٰرِ رَحْمَتِ ٱللَّهِ كَيْفَ يُحْىِ ٱلْأَرْضَ بَعْدَ مَوْتِهَآ إِنَّ ذَٰلِكَ لَمُحْىِ ٱلْمَوْتَىٰ وَهُوَ عَلَىٰ كُلِّ شَىْءٍ قَدِيرٌ

So observe the effects of the mercy of Allah - how He gives life to the earth after its lifelessness. Indeed, that [same one] will give life to the dead, and He is over all things competent.

Surah Ar-Room (30), ayah 50 · Saheeh International

Why this ayah: Allah reviving the earth after its death: the picture behind the book's title.

In the Ihya

إحياء: 105 times in the Ihya.