ک ت مk-t-m
(ن) كَتَمَ يَكْتُمُ كَتْمًا وَكِتْمَانًاkatama yaktumu katman wa-kitmānan: to hide, to keep secret; it involves not mere hiding but also withholding and suppressing a matter, which is why in the Quran it occurs mostly for concealing testimony and knowledge of the truth. ﴿وَلَا تَكْتُمُوا الشَّهَادَةَ﴾ (Al-Baqarah 2:283); ﴿اِنَّ الَّذِيْنَ يَكْتُمُوْنَ مَآ اَنْزَلْنَا مِنَ الْبَيِّنٰتِ وَالْهُدٰى﴾ (Al-Baqarah 2:159); ﴿وَاللّٰهُ مُخْرِجٌ مَّا كُنْتُمْ تَكْتُمُوْنَ﴾ (Al-Baqarah 2:72)Note: the word «يُخْفِيْنَyukhfīna» in Sūrat al-Nūr (24:31) is not from this root but from kh-f-y.