لهب doesn't appear in Hans Wehr's Modern Standard Arabic dictionary, but Lane's Arabic-English Lexicon has 5 entries for it, distinguished by diacritics. Select one below for the full classical Arabic definition.

• لَهِبَ Form 1

  1 لَهِبَ ذ , aor. لَهَبَ , (inf. n. لَهَبٌ, S,) (tropical:) He thirsted; was thirsty: (S, K:) [probably, burned with thirst].…

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• لهّب Form 2

  2 لهّب النَّارَ ذ [same as , except that it has an intensive signification; He made the fire to flame, or blaze, fiercely, or intensely: or, to flame, or blaze, without smoke, fiercely, or intensely.] (K.)…

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• لَهْبٌ

  لَهْبٌ ذ : see لَهَبٌ.…

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• لِهْبٌ

  لِهْبٌ ذ A gap, or space, between two mountains: (S, K:) or a cleft, or fissure, in a mountain: (Lh, K:) or a small gap, or ravine, such as is termed شِعْبٌ, in a mountain: (K:) or a cleft in a mountain, afterwards widen…

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• لَهَبٌ

  لَهَبٌ ذ and (K) and and and (S, K), [inf. ns., of which the verb, لَهِبَ, aor. لَهَبَ , does not appear to have been used in the classical ages,] The flaming, or blazing, of fire: (S:) or its flaming, or blazing, free f…

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