س ت رs-t-r
(ض) سَتَرَ يَسْتِرُ سَتْرًاsatara yastiru satran: to cover a thing; to conceal.
سِتْرٌsitr (noun, ism dhāt): anything by which something is concealed; a screen; a veil. ﴿لَمْ نَجْعَلْ لَّهُمْ مِّنْ دُوْنِهَا سِتْرًا﴾ (Al-Kahf 18:90)
مَسْتُوْرٌmastūr (passive participle, ism mafʿūl): covered; concealed. ﴿حِجَابًا مَّسْتُوْرًا﴾ (Al-Isrāʾ 17:45)
Form VIII (iftiʿāl) اِسْتَتَرَ يَسْتَتِرُ اِسْتِتَارًاistatara yastatiru istitāran: to be covered; to hide oneself; to screen oneself. ﴿وَمَا كُنْتُمْ تَسْتَتِرُوْنَ اَنْ يَّشْهَدَ عَلَيْكُمْ سَمْعُكُمْ﴾ (Fuṣṣilat 41:22)