شَهْرٍ

A word in the Arabic language will either be 1) a verb or 2) a noun or 3) a particle – شَهْرٍ is a noun

A noun may either be 1) Definite or indefinite 2) Masculine or feminine 3) Singular, dual or plural 4) Nominative, accusative or genitive

شَهْرٌ is the natural state of this indefinite noun and it becomes شَهْرٍ due to: 1) a preposition that precedes it or 2) a possessed noun that precedes it or 3) it’s a noun of dependent declension a) نَعْتٌ / صِفَطٌ adjectives b) التَّوْكِيْدُ emphatic c) المَعْطُوْفٌ conjunction d) البَدَلُ synonym

Month, Moon, New moon, Full moon

To publish abroad, Divulge

نَكِرَةٌمُفْرَدٌمُذَكَّرٌمَجْرُوْرٌش ه ربَاب فَتَحَشَهَرَ يَشْهَرُفَعْلٌاسْمٌالْمَصْدَرُ
IndefiniteSingularMasculineGenitiveRootMonthsفPatternNounVerbal noun
Surah/Below is the only verse in the holy Quran containing the genitive nounشَهْرٍ
Verse
97-3The night of Qadr is better than a thousand monthsلَيْلَةُ القَدْرِ خَيْرٌ مِّنْ أَلْفِ شَهْرٍ