The correct spelling of the phrase "more decreasing" is /mɔːr dɪˈkriːsɪŋ/. The first syllable "more" is spelled as it sounds, with the vowel sound pronounced as in "door". The second word "decreasing" has a stress on the second syllable and is spelled with "ea" because it comes from the root word "decrease". The "ea" in this case is pronounced as "ee". Thus, the word is spelled phonetically with a combination of both sound and etymology.
The phrase "more decreasing" is not a common phrase or an established word itself. However, let's break down the etymology of each individual word:
1. More: The word "more" originated from the Old English word "māra", meaning "greater in amount, number, or size". It further traces back to the Proto-Germanic word "maizô" and the Proto-Indo-European root "mei-" which conveys the concept of "great" or "big".
2. Decreasing: The word "decreasing" comes from the verb "decrease". "Decrease" originated from the Old French word "descroistre" (Modern French: "décroître"), which has its roots in the Latin term "decrescere".