ضحك doesn't appear in Hans Wehr's Modern Standard Arabic dictionary, but Lane's Arabic-English Lexicon has 2 entries for it, distinguished by diacritics. Select one below for the full classical Arabic definition.

• ضَحِكَ Form 1

  1 ضَحِكَ ذ , (S, MA, O, Msb, K, &c.,) and some say ضِحِكْتُ, with kesr to the ض, (TA, as from the K, [but not in the CK nor in my MS. copy of the K,]) to agree with the vowel of the ح because the latter is a faucial lett…

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• ضَحْكٌ

  ضَحْكٌ ذ [originally an inf. n., a contraction of ضَحِكٌ,] The appearance, or appearing, of the central incisors [or of the front teeth] by reason of happiness, joy, or gladness. (TA.) -b2- And hence, (TA,) Wonder. (K, T…

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