The spelling of the word "hennigan" follows the English language's system of phonetic transcription. The word is pronounced as /hɛnɪɡən/ where the first syllable is pronounced as 'hen' with a short 'e' sound, followed by 'ni' with a short 'i' sound and ending with 'gan' with a soft 'g' sound. The word is simple and easy to spell once its pronunciation is learnt.