-ઈ

• For the relational suffix, inherited from Sauraseni Prakrit -𑀇𑀅 (-ia), from Sanskrit -इक (-ika) or Sanskrit -ईय (-īya), from Proto-Indo-European *-iHyos.
• For the possessive suffix, borrowed from Sanskrit -ई (-ī), from Proto-Indo-European *-inos.
• For the feminine suffix, borrowed from Sanskrit -ई (-ī), from Proto-Indo-European *-ih₂.
• For the feminine nouns, ultimately Sanskrit -इका (-ikā).

The first two uses were also influenced by the unrelated Classical Persian ـی (-ī) and Arabic ـِيّ (-iyy, nisba suffix).

-ઈ • (-ī)

1. forms nouns and adjectives implying relation or association

   ‎કચ્છ (kacch, “Kutch”) + ‎-ઈ (-ī) → ‎કચ્છી (kacchī, “Kutchi”)

   ‎દોસ્ત (dost, “friend”) + ‎-ઈ (-ī) → ‎દોસ્તી (dostī, “friendship”)

   ‎પહાડ (pahāḍ, “mountain”) + ‎-ઈ (-ī) → ‎પહાડી (pahāḍī, “mountainous”)

2. forms nouns and adjectives indicating possession of or having a property or quality

   ‎જરૂર (jarūr, “necessity”) + ‎-ઈ (-ī) → ‎જરૂરી (jarūrī, “necessary”)

3. suffix of feminine marked singular nouns
4. suffix of feminine marked adjectives

   ‎ઊંચું (ū̃cũ, “tall”) + ‎-ઈ (-ī) → ‎ઊંચી (ū̃cī, “tall (feminine)”)