A language may spell some words with unpronounced letters that exist for historical or other reasons.
ɐ lˈæŋɡwɪdʒ mˈeɪ spˈɛl sˌʌm wˈɜːdz wɪð ʌnpɹənˈaʊnst lˈɛɾɚz ðæt ɛɡzˈɪst fɔːɹ hɪstˈɔːɹɪkəl ɔːɹ ˈʌðɚ ɹˈiːzənz.