The spelling of "most halfformed" is a bit unusual. The word "most" is spelt as it is normally pronounced, with the long o sound /oʊ/ and the s consonant sound /s/. However, "halfformed" is spelt with two f's, reflecting the fact that the word is a combination of "half" and "formed". The double f's indicate that the sound in the middle of the word is a voiceless fricative /f/ sound, rather than a voiced /v/ sound. The pronunciation of "halfformed" would be /ˌhælˈfɔrmd/.
The term "most halfformed" does not have a well-known etymology as it is not a commonly used word or phrase. It appears to be a combination of the words "most" and "half-formed", but it doesn't have a specific historical origin or linguistic basis that can be identified. It is possible that it was created for a specific context or usage, but without further information, it is difficult to ascertain its precise etymology.