مُمَدَّدَةٍ

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

مُمَدَّدَةٌ is the natural state of this indefinite noun and it becomes مُمَدَّدّةٍ 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

Outstretched, streched forth

To be advanced (day) to stretch forth, extend, draw out, cause to increase or abound, draw forth, spread wide, strain, manure (a land), take ink, prolong