The word "haddest coming" is a past participle form of the verb "to have" in the second person singular. The spelling of this word can be explained using IPA phonetic transcription as /ˈhædəst ˈkʌmɪŋ/. The "a" in "haddest" is pronounced as the short vowel "æ," while the "e" in "coming" is pronounced as the short vowel "ʌ." The "-est" ending in "haddest" is a suffix denoting the superlative form of the verb. Overall, "haddest coming" denotes that you have come at a specific time in the past.
The phrase "haddest coming" is not a commonly used expression in modern English. It seems to be a combination of the past tense of the verb "to have" (had) and the word "coming".
However, if we break it down, the word "coming" originates from the Old English word "cuman", which means "to come". "Coming" is the present participle form of this verb, which is used to express an action that is happening at the present time.
On the other hand, "had" comes from the Old English word "habban", which means "to possess" or "to hold". In modern English, "had" is used as the past tense of "to have".