The correct spelling of the phrase "more tough nut" is /mɔːr tʌf nʌt/. The word "tough" is spelled with the letters "ou" instead of just "o" because it is a diphthong, meaning two vowel sounds are pronounced together. In this case, it is a combination of the "oh" and "oo" sounds. Additionally, the word "nut" is spelled with a "u" instead of an "i" because it is a short vowel sound, making the "u" more appropriate than the "i" in "nut."
The phrase "more tough nut" refers to an individual or situation that is even more challenging, resistant or difficult to overcome than the typical or already challenging circumstances. It carries a connotation of increased complexity or obstacles to be faced when compared to a regular or initial difficulty.
This idiomatic expression is derived from the metaphorical usage of the term "tough nut," which is often used to describe a problem, challenge, or person who is particularly difficult to deal with or to win over. When the word "more" is added to describe a "tough nut," it signifies an escalation of the level of difficulty or resistance involved.
The phrase is often employed in a figurative sense to describe a wide range of situations or individuals that present enhanced challenges. It could refer to a formidable opponent in a competitive context, a complex issue that is difficult to resolve, an arduous task or project that requires exceptional effort and skill, or even a person who possesses a more stubborn or resistant nature. Usage of "more tough nut" serves to emphasize the severity, toughness, or resistance that one is facing, adding an extra layer of intensity to the challenge at hand.