الزَّيْتُوْنِ

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

الزَّيْتُوْنُ is the natural state of this definite noun and it became الزَّيْتُوْنِ 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

Olive, Olive tree

To dress food with oil, anoint with oil, give oil

Verse/Below is the only verse in the holy Quran, containing the genitive nounالزَّيْتُوْنِ
Ayat
95-1By the fig and the oliveوَالتِّيْنِ وَالزَّيْتُوْنِ