Core sense — it became heaped up, accumulated, one part on anothergenerated
6.1figurative · مجازit became heaped up, or accumulated, one part on another—ارتكم
the clouds became heaped up, one above another—تراكم السَّحَابُ
Said of a thing.
Also تراكب, mentioned in the article ركب.
[the flesh of the she-camel became accumulated]—تراكم لَحْمُ النَّاقَةِ
Meaning: the she-camel became fat.
[the darkness became dense]—تراكمت الظَّلْمَةُ
The Arabs describe thick darkness as “darknesses one above another”: see Qur 24:40.
[occupations became accumulated]—تراكمت الأَشْغَالُ
[the occupations became accumulated]—ارتكمت
Qur’ān 24:40 approximate — somewhere between 24:31 and 24:43 Lane cites “Kur xxiv. 40”
Qur’ān 24:43 located by this root inside the range Lane’s citation allows
أَلَمْ تَرَ أَنَّ ٱللَّهَ يُزْجِى سَحَابًا ثُمَّ يُؤَلِّفُ بَيْنَهُۥ ثُمَّ يَجْعَلُهُۥ رُكَامًا فَتَرَى ٱلْوَدْقَ يَخْرُجُ مِنْ خِلَـٰلِهِۦ وَيُنَزِّلُ مِنَ ٱلسَّمَآءِ مِن جِبَالٍ فِيهَا مِنۢ بَرَدٍ فَيُصِيبُ بِهِۦ مَن يَشَآءُ وَيَصْرِفُهُۥ عَن مَّن يَشَآءُ ۖ يَكَادُ سَنَا بَرْقِهِۦ يَذْهَبُ بِٱلْأَبْصَـٰرِSeest thou not that Allah makes the clouds move gently, then joins them together, then makes them into a heap? - then wilt thou see rain issue forth from their midst. And He sends down from the sky mountain masses (of clouds) wherein is hail: He strikes therewith whom He pleases and He turns it away from whom He pleases, the vivid flash of His lightning well-nigh blinds the sight.Abdullah Yusuf Ali, The Holy Qur’ān (1934)
Show Lane's original text
and ارتكم It (a thing) was, or became heaped, or piled, up, or together, or accumulated; i. e., collected together, (S, K, TA,) one part upon [or overlying] another. (TA.) You say, تراكم السَّحَابُ The clouds were, or became, [heaped, or piled, up,] one above, or upon, [or overlying,] another; as also تراكب . (TA in art. ركب .) And تراكم لَحْمُ النَّاقَةِ [lit. The flesh of the she-camel became accumulated]; meaning the she-camel became fat. (TA.) [And تراكمت الظَّلْمَةُ The darkness became condensed, or dense: for the Arabs describe thick darkness as “ darknesses one above another: ” see Kur xxiv. 40.] And تراكمت الأَشْغَالُ and ارتكمت [Occupations, or the occupations, became accumulated]. (TA.)