الشَّمْسِ

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

الشَّمْسُ is the natural state of this definite noun and it changes to الشَّمْسِ 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

Sun

To be bright with sunshine, be glorious, be sunny

مَعْرِفَةٌمُفْرَدٌمُؤَنَّثٌمَجْرُوْرٌش م سبَاب ضَرَبَ شَمَسَ يَشْمِسُفَعْلٌاسْمٌاِسْمُ الجِنْسِ
DefiniteSingularFeminineGenitiveRootThe Sunض / نPatternNounGeneric or common Noun
Surah/Below are the 9 verses in the holy Quran containing the nounالشَّمْسِ
Verse 
Did not you see to those who argued with Ebrahim (AS) concerning his Lord that Allah (SWT) gave himأَلَمْ تَرَ إِلَى الَّذِي حَآجَّ إِبْرَاهِيْمَ فِى رَبِّهِ أَنْ ءَاتَيْنَاهُ اللهُ
the kingdom? when Ebrahim (AS) said, “My Lord is He who grants life and causes death”المُلْكَ إِذْ قَالَ إِبْرَاهِيْمُ رَبِّيَ الَّذِى يُحْيِى وَيُمِيْتُ
he said, “I give life and I cause death”قَالَ أَنَاْ أُحْيِى وَأُمِيْتُ
Ebrahim (AS) said, “then indeed, Allah (SWT) brings up the sun (comes) from the eastقَالَ إِبْرَاهِيْمُ فَإِنَّ اللهَ يَأْتِى بِالشَّمْسِ مِنَ المَشْرِقِ
so, you bring it from the west”فَأْتِ بِهَا مِنَ المَغْرِبِ
2-258so, the one who disbelieved became dumbfounded and Allah (SWT) guides not the wrong-doing peopleفَبُهِتَ الَّذِي كَفَرَ وَاللهُ لَا يَهْدِى القَوْمَ الظَّالِمِيْنَ
17-78
18-86
18-90
20-130
27-24
41-37
50-39
91-1By the sun and its brightnessوَالشَّمْسِ وَضُحَاهَا