صرطIbn Fāris gives no independent meaning for ṣ-r-ṭ. He files it under substitution, refers … (root srt)

The lexicographers in chronological order, from al-Khalīl to Lane.

No entry from al-Khalīl is supplied. The earliest witness here is al-Jawharī, who lists ṣirāṭ, sirāṭ and zirāṭ as one word for 'road' and cites a verse on 'the plain open part (waḍaḥ) of the ṣirāṭ'. Ibn Fāris gives the root no meaning of its own: he says it belongs to the chapter of substitution, points to the sīn entry, and repeats the gloss 'the road' with the same verse. Al-Rāghib narrows the gloss to 'the straight road', citing Q 6:153, and notes the variant sirāṭ. Ibn Manẓūr, through al-Azharī, records that most of the Seven Readers read Q 1:6 with ṣād and Yaʿqūb with sīn, and explains that the original sīn became ṣād next to ṭāʾ because the two are close in articulation. Lane (after the Tāj) calls sirāṭ the original form, notes that the Ḥijāz made the word feminine and Tamīm masculine, and adds the eschatological sense: a bridge over Hell, 'sharper than a sword and thinner than a hair'.

What the theorists of sound symbolism would say of these letters. Speculative by nature.

In the data given, Ibn ʿArabī assigns rāʾ to the Fifth Heaven and ṭāʾ to the Sixth, and gives no heaven for ṣād. Read symbolically, the word would climb through the two upper spheres. In al-Dabbāgh's scheme, ṣād is 'all the dust of the earth at the Standing before God', rāʾ indicates 'all goods, outward and inward', and ṭāʾ indicates what is 'pure and clear to the utmost'. Joined, these would suggest a passage from the ground of Judgement toward purity, which matches the eschatological bridge suggestively. For Ibn Jinnī, the relevant point is phonetic: the emphatic ṣād is an assimilation to ṭāʾ and was not chosen for meaning. Mainstream linguistics treats all such letter-meaning readings as suggestive at most.

The two-letter nucleus (Ibn Fāris's own chapters) and the permutations of the letters (Ibn Jinnī).

Ibn Fāris places ṣ-r-ṭ in the ṣ-r chapter among roots with full meanings of their own: ṣ-r-ʿ (falling to the ground), ṣ-r-f (turning back), ṣ-r-m (cutting), ṣ-r-y (gathering), ṣ-r-ḥ (appearing and standing out), ṣ-r-kh (a loud cry) and ṣ-r-d (cold, purity, scarcity). Because ṣ-r-ṭ is a substitution for s-r-ṭ, it has no organic place in this nucleus, and any link to these siblings is juxtaposition only. Of the permutations, only ṣ-ṭ-r is attested. It shows the same pattern in reverse: it is the ṣād variant of s-ṭ-r ('line, row'), and the muṣḥaf writes muṣayṭir with ṣād at Q 52:37 and 88:22. Ibn Jinnī's greater derivation does not fit well here, since the letter set is phonetically conditioned. The more relevant framework is his and Sībawayh's treatment of sīn becoming ṣād before emphatic and back consonants.

Cognates in the sister languages, and whether the word was borrowed.

The word has no native Semitic cognate. Jeffery and earlier Western scholarship derive sirāṭ/ṣirāṭ from Latin strata ('paved road'), through Greek and then Aramaic/Syriac isṭrāṭā. Arabic dropped the Aramaic prothetic vowel and later made the sīn emphatic under the influence of ṭāʾ. This account fits the Arab lexicographers' own report that the sīn form is original and that ṣirāṭ is a substitution. The eschatological sense of a bridge over Hell is a later Islamic development and is not inherited from the Latin or Aramaic word.

How the classical exegetes read the word in the Quran.

At Q 1:6–7, al-Ṭabarī glosses al-ṣirāṭ al-mustaqīm as the clear road without crookedness. He reports readings of it as Islam, the Book of God, or the way of the Prophet and his two successors, and understands the petition as a request to be kept firm on what pleases God. Al-Zamakhsharī discusses the sīn, ṣād and zāy-coloured (ishmām) readings, and treats 'the path of those You have blessed' as an apposition (badal) that explains which straight path is meant. Al-Rāzī develops the point that the straight way is one while deviations are many, which fits the Quran's pattern at Q 6:153: one ṣirāṭ, set against the plural subul. The Quran never uses ṣirāṭ in the plural, and al-Rāghib's gloss 'the straight road' reflects that usage.

The word in Ibn ʿArabī's text and terminology.

The root does not occur in Faṣṣ Ādam, and Ibn ʿArabī's Iṣṭilāḥ gives no definition of it. His main treatment is in the Hūd chapter of the Fuṣūṣ, on Q 11:56: 'there is no creature but He holds it by its forelock; my Lord is on a straight path'. He reasons that every creature walks the Lord's straight path in the respect that it is held by Him. In that respect it is neither among those 'with whom He is angry' nor among 'those who go astray'. The Quran's single ṣirāṭ thus becomes a universal path, alongside the particular path of the revealed Law.