The standard lexica (BDB, HALOT, DCH) and the TDOT article by Hamp and Botterweck agree that this verb names the decisive act of rendering and executing a verdict, with a marked bias toward vindicating the wronged rather than condemning the wicked. It is the rarer, more strictly forensic counterpart of the common verb for judging and governing (šāpaṭ), concentrated in poetry, the Song of Moses, the Psalms, the prophets, and royal wisdom. Gerhard Liedke (TLOT) argues that šāpaṭ restores disturbed community order in the broadest sense while dîn is narrowly the verdict itself; Bovati, Niehr, and Mafico reinforce the contrast. The cognate-accusative phrase pairing this verb with its noun functions as a fixed idiom for championing a legal cause (Lundbom), and its closest ancient twin is the Ugaritic Aqhat formula in which King Danel at the gate judges the cause of the widow and adjudicates the case of the orphan, the same word-pair (dn / ṯpṭ) that stands behind dîn / šāpaṭ in Psalm 72:2, Isaiah 3:13, and Jeremiah 5:28; 22:16. Of roughly two dozen occurrences, fewer than five carry clearly condemnatory force; the rest vindicate the innocent, with the recurring poor-orphan-widow formula, or denote governance, the bias toward rescue running about four to one. The root is securely Proto-Semitic, with cognates across the Semitic family (Akkadian dânu/dīnu/dayyānu, Ugaritic dn, and a dense Aramaic tradition), and through Aramaic it furnishes the later vocabulary for court and final judgment, including the courtroom scene of Daniel 7 and the rabbinic bêt dîn and yôm ha-dîn. Whether the Hebrew root is one polysemous lexeme or two early-merged sub-roots (one "judge/litigate," one "rule/govern") is a question BDB left open and TWOT still flags, though HALOT, DCH, and TDOT prefer a unitary analysis.
Two crux verses sit at the philological edges of the root, and in both the ordinary English "judge" is the wrong gloss, for opposite reasons. In Genesis 6:3 the hapax form יָדוֹן is genuinely contested, and the literature carries at least six rival derivations; the Masoretes pointed it as if from a hollow root דּוּן, but no such verb is otherwise clearly attested and the expected imperfect of דִּין would be יָדִין. BDB files it under דִּין while itself disowning the AV "strive" gloss; HALOT, DCH, and Gesenius (18th ed.) instead posit a separate near-homophonic root דּוּן II "remain," the case for which C. Rabin developed ("Etymological Miscellanea," Scripta Hierosolymitana 8 [1961]: 386-400, esp. 388-89), connecting it also to Genesis 30:6. The ancient versions converge on "abide/remain": LXX καταμένω, with the demonstrative τούτοις narrowing the threat to the Flood generation; Vulgate permanebit; the Samaritan Pentateuch's independent Hebrew ידור "dwell"; the Peshitta; and Targum Onkelos's interpretive יִתְקַיֵּם "endure." Only Symmachus and Aquila revert to a דִּין-based κρινεῖ. A live question is whether that versional convergence preserves a genuine second root or merely reflects contextual paraphrase, possibly of a source text that itself read יָדוּר "dwell". Modern commentators (Skinner, Westermann, Wenham, Hamilton, Sarna, Arnold, Alter) lean to "remain" and read the 120 years as a lifespan cap, the clause בְּשַׁגַּם הוּא בָשָׂר ("inasmuch as he is also flesh") fitting the mortal-substrate reading; Mathews defends "contend/strive" and a pre-Flood probation, in line with the 1 Peter 3:20 reception. Among further minority proposals, Speiser read a "shield/surrogate" sense from Akkadian dinānu/andunānu ("my spirit shall not shield man forever") and dismissed Cassuto's rival Akkadian etymology, Scharbert an Arabic "be humbled" (followed by the Jerusalem Bible), von Rad and Gunkel a "rule/prevail" sense, Cassuto a postulated Akkadian "be fixed, remain," and Skinner and others note an emendation to יָדוּר or יָלִין "dwell, lodge"; none commanded assent, and Hamilton candidly concedes the verdict for "remain" is one of preference, not proof. Ecclesiastes 6:10 is the opposite case: the form לָדִין is morphologically transparent (the infinitive of דִּין), but the sense is the late, forensic, Aramaic-colored "to litigate, contend at law" rather than "to render verdict." The construction with עִם ("contend with" a counterparty, as against the direct object or ל of the older "judge" sense), the Aramaism תַּקִּיף for the stronger party, the deliberate choice of this verb over the older רִיב (which Qoheleth's late Hebrew elsewhere replaces with מִשְׁפָּט for general judgment), and the versions (LXX κριθῆναι μετά, standard for going to law with someone; Vulgate in iudicio contendere; the Targum's לְמֵיקַם בְּדִינָא) all fix this reading; the lexica (BDB, HALOT, DCH, Gesenius 18) concur. The stronger party is near-universally taken to be God (Seow, Fox, Longman, Murphy, Crenshaw, Krüger, Lohfink, Whybray, Gordis, Schoors, Barton, Weeks, and others; the dissents are minor, Rashi reading the Angel of Death and the UBS Handbook leaving it open), gathering the Joban lawsuit-against-God motif (Job 9:3; 40:2; Isaiah 45:9; Jeremiah 12:1) into a verse that declares the suit futile because the event has already been "named." Scholars divide on what that naming means: a decree fixed in advance (Seow), the settled identity or essence of a thing (Lohfink), or simply the fixity of the future (Fox). The wordplay on naming echoes Genesis 1-2, and the ambiguity of אָדָם (humanity generally or Adam specifically) plays into it. The opening clause nearly repeats Ecclesiastes 3:15 and the unit prepares the question of 7:13; Rudman makes the verse a keystone of a determinist reading of the book, while others (Whybray, Lohfink, Krüger, Weeks) read its determinism as moderated by acceptance and Fox as absurdism rather than determinism proper.