جِيْدِ

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

الجِيْدُ is the natural state of a definite noun and becomes الجِيْدِ 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

الجِيْدِ loses it’s definite article, becoming جِيْدِ due to it being a possessed noun

Grammatical analysis of جِيْدِ
اسْمٌ مَجْرُوْرٌ بِالكَسْرَةِ الزَّاهِرَةِ وَهُوَ مَضَافٌ 
مَعْرِفَةٌمُفْرَدٌمُذَكَّرٌمَجْرُوْرٌج ي دبَاب سَمِعَفِعْلٌجَادَ يَجَادُاسْمٌاِسْمُ الجِنْسِ
DefiniteSingularMasculineGenitiveRootNeck ofPatternسNounGeneric or common Noun
Grammatical analysis of جِيْدِ
اسْمٌ مَجْرُوْرٌ بِالكَسْرَةِ الزَّاهِرَةِ وَهُوَ مَضَافٌ
Surah/Below is the only verse in the holy Quran containing the genitive, possessed nounجِيْدِ
Verse
111-5In her neck a rope of twisted fiberفِيْ جِيْدِهَا حَبْلٌ مِّنْ مَّسَدٍ