1. The root and its core meaning

The root ك ظ م (kāf – ẓāʾ – mīm) turns on one idea: to hold something in, and to seal shut a thing that is full. The lexicographers fix its core sense as imsāk (retaining, holding back) and radd (pushing back) — the act of closing off a passage so that what is inside cannot escape.

The Form-I verb is كَظَمَ يَكْظِمُ كَظْمًا (kaẓama, yakẓimu, kaẓman) — “he held it in / sealed it shut.” Its verbal noun is kaẓm, and (for the camel, below) kuẓūm.

The master image: a full vessel tied closed. Everything the root produces keeps returning to fullness under a seal.

2. The lexical fan (how the Arabs used the root)

Before the Qurʾān, the root already spread across vivid everyday usages — gathered here from the commentators on 3:134:

• The waterskin: kaẓamtu al-siqāʾ / al-qirba — “I filled the waterskin and tied its mouth shut.” (Qurṭubī, Ṭabarī, Rāzī, Ālūsī, Ibn ʿĀshūr)
• The seal/strap: the kiẓām is the strap that closes the skin’s mouth; the kiẓāma (or sidāda) is whatever you block a watercourse, door, or road with. (Qurṭubī, Rāzī)
• The bowstring strap: the kiẓāma is also the thong that binds the bowstring tight onto the tip of the bow — a thing held under full tension. (Zajjāj)
• Water-channels: kaẓāʾim are conduits that run from well to well, full of water like sealed skins. (Qurṭubī, Ṭabarī, Rāzī, Zajjāj)
• The windpipe: akhadha bi-kaẓmihi — “he seized him by his breath-passage,” the throat being the place that fills with breath. (Ṭabarī, Rāzī)
• The camel’s cud: kaẓama al-baʿīr jirratahu (kuẓūman) — the camel held its cud down in its belly and stopped chewing, especially out of fear and strain. (Zajjāj, Rāzī, Ṭabarī, Qurṭubī)
• A place-name: Kāẓima, a spot in the desert. (Zajjāj)

Every one of these is the same picture: filled, and held/sealed shut.

3. The Qurʾānic forms of the root

The Qurʾān uses the root in three morphological shapes, which fall along an active ↔ passive spectrum:

Note the spectrum. Kāẓim is the one who seals (active); makẓūm is the one who is sealed upon (passive); kaẓīm sits between, naming a person brimful and held in. The shape of the word already tells you whether the person is mastering the fullness or being mastered by it.

4. The six occurrences, one by one

(1) Āl ʿImrān 3:134 — al-kāẓimīn al-ghayẓ — the praised holding-in

﴿وَٱلۡكَـٰظِمِینَ ٱلۡغَیۡظَ﴾ — “and those who restrain their anger.”

Active participle + object: the believers who seal their anger shut while fully able to act on it. This is the one occurrence where kaẓm is a chosen virtue — done deliberately, for Allah — and it is rewarded with His love. Here the person is the master of his fullness.

(2) Yūsuf 12:84 — kaẓīm — grief held in (Yaʿqūb)

﴿وَٱبۡیَضَّتۡ عَیۡنَاهُ مِنَ ٱلۡحُزۡنِ فَهُوَ كَظِیمٌ﴾ — “and his eyes whitened from grief, for he was kaẓīm.”

Yaʿqūb, grieving for Yūsuf until his sight faded, is kaẓīm — filled with sorrow and holding it in, not pouring his complaint out to people. (Two verses later he says he complains of his grief only to Allah, 12:86.) Here holding-in is the dignified, prophetic bearing of sorrow.

(3) an-Naḥl 16:58 — kaẓīm — choked rage at a daughter

﴿وَإِذَا بُشِّرَ أَحَدُهُم بِٱلۡأُنثَىٰ ظَلَّ وَجۡهُهُۥ مُسۡوَدࣰّا وَهُوَ كَظِیمٌ﴾ — “and when one of them is given news of a female, his face darkens and he is kaẓīm.”

The pagan, on hearing he has a daughter, goes dark-faced and kaẓīm — brimful of suppressed rage and grief. Here the very same “fullness held in” is blameworthy: a heart choking with fury at one of Allah’s gifts. (The root is morally neutral; what fills you, and why, decides its worth.)

(4) az-Zukhruf 43:17 — kaẓīm — the same, sharpened into hypocrisy

﴿وَإِذَا بُشِّرَ أَحَدُهُم بِمَا ضَرَبَ لِلرَّحۡمَٰنِ مَثَلࣰا ظَلَّ وَجۡهُهُۥ مُسۡوَدࣰّا وَهُوَ كَظِیمٌ﴾ — “and when one of them is given news of what he ascribes to the Most Merciful, his face darkens and he is kaẓīm.”

The same dark, choked state — but the irony is now exposed: they assign daughters to Allah (claiming the angels are His daughters), yet are filled with choked grief when given a daughter themselves.

(5) Ghāfir 40:18 — kāẓimīn — hearts choked with terror on the Day

﴿وَأَنذِرۡهُمۡ یَوۡمَ ٱلۡـَٔازِفَةِ إِذِ ٱلۡقُلُوبُ لَدَى ٱلۡحَنَاجِرِ كَـٰظِمِینَ﴾ — “and warn them of the Day of the Approaching, when hearts are at the throats, kāẓimīn.”

On Judgment Day, hearts rise to the throats (ḥanājir — the very breath-passages of the lexical “windpipe” sense), and the people are kāẓimīn — choked, holding in their terror, unable to release or swallow it. Note: it is the active participle, the same word as 3:134 — yet here the people are overwhelmed by their fullness, not masters of it.

(6) al-Qalam 68:48 — makẓūm — distress held in (Yūnus)

﴿وَلَا تَكُن كَصَاحِبِ ٱلۡحُوتِ إِذۡ نَادَىٰ وَهُوَ مَكۡظُومٌ﴾ — “and be not like the companion of the fish, when he called out while he was makẓūm.”

Yūnus, in the belly of the fish, called out while makẓūm — filled and choked with distress. The passive participle is exact: he is the one acted upon, sealed-in by his anguish.

5. The thread that ties all six together

One image: in every case, a person is filled to the brim with something — anger (3:134), grief (12:84; 68:48), choked rage (16:58; 43:17), or terror (40:18) — and that fullness is held inside under a seal. The root never loses its waterskin.

The decisive variable is who is in control:

• In 3:134, the believer is the kāẓim — he does the sealing, by choice, for Allah → praised, beloved.
• In 40:18, the disbelievers are also called kāẓimīn — but their hearts are at their throats; they are sealed-upon by dread, mastered by what fills them → terror.