The spelling "haddest being" is not commonly used in modern English. It appears to be an outdated form of the verb "have" in the past tense, and the word "being" which means existence. The pronunciation would be /ˈhædɪst ˈbiːɪŋ/, with the stress on the first syllable of each word. However, it is usually not necessary to use such archaic spellings in daily conversation or writing, as the standard modern spellings of these words are typically more appropriate.
The phrase "haddest being" does not have a specific etymology on its own. However, it comprises two separate parts:
1. "Haddest": It is the second-person singular past tense of the verb "have", in the indicative mood. This form is used to describe an action that took place in the past. The word "have" has Old English roots and can be traced back to the Proto-Germanic word "haban", meaning "to have" or "hold".
2. "Being": It is the present participle of the verb "be". The word "be" has Old English origins and its etymology can be traced back to the Proto-Germanic word "ben", meaning "to be".
In combination, "haddest being" suggests someone or something possessing or owning existence in the past.