وَسَطْنَ

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

A verb will either be: 1) past tense or 2) present or future tense or 3) a command or request verb, also called an imperative – وَسَطْنَ is a past tense verb

They (feminine) penetrated into the midst

To be in the midst, penetrate into the midst, be good and exalted, occupy the middle position

مُعْتَلُّ الْفَاءِالْغَائِبُ هُنَّاَلْمِثَالُفِعْلٌ تَامٌّو س طوَسَطَ يَسِطُبَابٌ ضَرَبَ 
Weak 1st rad.Subject TheyWeak VerbComplete verbRootاَلْمِثَالُاَلْمَصْدَرُ
فِعْلٌ
Verb of command/Requestفِعْلُ أَمْرٍPresent and future tense verbفِعْلٌ مُضَارِعٌPast tense verbفِعْلٌ مَاضٍ
He/It centersيَسِطُHe centeredوَسَطَ
They two centerيَسِطَانِThey two centeredوَسَطَا
They all centerيَسِطُوْنَThey centeredوَسَطُوْا
She centersتَسِطُShe centeredوَسَطَتْ
They two (feminine) centerتَسِطَانِThey two (feminine) centeredوَسَطَتَا
They all (feminine) centerيَسِطْنَThey (feminine) centeredوَسَطْنَ
centerسِطْYou centerتَسِطُYou centeredوَسَطْتَ
You two centerسِطَاYou two centerتَسِطَانِYou two centeredوَسَطْتُمَا
You all centerسِطُوْاYou all centerتَسِطُوْنَYou all centeredوَسَطْتُمْ
You (feminine) centerسِطِيYou (feminine) centerتَسِطِيْنَYou (feminine) centeredوَسَطْتِ
You two (feminine) centerسِطَاYou two (feminine) centerتَسِطَانِYou two (feminine) centeredوَسَطْتُمَا
You all (feminine) centerسِطْنَYou all (feminine) centerتَسِطْنَYou all (feminine) centeredوَسَطْتُنَّ
I centerأَسِطُI centeredوَسَطْتُ
We centerنَسِطُWe centeredوَسَطْنَا
Surah/Below is the only verse in the holy Quran containing the third person, feminine, perfect verbوَسَطْنَ
Verse  
100-5penetrating forthwithفَوَسَطْنَ بِهِ جَمْعًا