Correct spelling for the English word "in vulnerable" is [ɪn vˈʌlnəɹəbə͡l], [ɪn vˈʌlnəɹəbəl], [ɪ_n v_ˈʌ_l_n_ə_ɹ_ə_b_əl] (IPA phonetic alphabet).
The word invulnerable comes from the Latin root invulnerabilis, which comprises the prefix in- meaning not or without, and the word vulnerabilis, meaning able to be wounded or capable of being harmed. The term invulnerable formed in the English language in the mid-17th century, retaining its original Latin meaning of immune to injury or harm.