The correct spelling of the phrase "most attaching" is debatable, as it is not a commonly used phrase. However, if we break down the individual sounds, it would be pronounced as /moʊst əˈtætʃɪŋ/. The "o" sound in "most" is pronounced as /oʊ/, while the "a" sound in "attaching" is pronounced as /æ/. The stress in the word falls on the second syllable, indicated by the apostrophe in the IPA transcription. Overall, the spelling of the word "most attaching" should be based on context and the intended meaning of the phrase.
The phrase "most attaching" is not a word in itself, but rather a combination of the adjective "most" and the verb "attach" in its present participle form.
The word "attach" comes from the Old French verb "atachier", which meant "to fasten, to fix". This, in turn, derived from the Vulgar Latin word "attaccare", meaning "to stick to, to adhere". The Latin word "attachare" also contributed to the formation of the word.
The use of the intensifying adverb "most" in combination with "attaching" implies that something is causing a strong or deep emotional connection, or is extremely endearing or engaging. However, it is worth noting that "most attaching" is not a commonly used phrase in English, and other adjectives like "endearing" or "captivating" are often preferred in such contexts.