To solve this problem, we need to determine the logic used in coding the words in the given code language.'CONFUSED' is coded as '7' and 'CHAIN' is coded as '4'. To find the pattern, let's analyze the coding of these words.

1. Evaluating the word 'CONFUSED':
   • The word 'CONFUSED' has 8 letters.
   • It is coded as '7'.
   • This indicates that the code is not directly related to the number of letters.
2. Evaluating the word 'CHAIN':
   • The word 'CHAIN' has 5 letters.
   • It is coded as '4'.
   • Similarly, the code is not directly related to the number of letters.

Now, we need to hypothesize that the pattern could be related to something other than just counting letters or another simple pattern like vowel count or frequency of certain characters.

3. Discover the pattern:
   • Let’s count the number of vowels in each word:
   • 'CONFUSED' has vowels: O, U, E = 3 vowels. However, it is coded as '7'.
   • 'CHAIN' has one vowel, A = 1 vowel. However, it is coded as '4'.
   • The hypothesis about vowels doesn't directly match the code number alone.
   • Another pattern to try is to count consonants: 'CONFUSED' has 5 consonants, it seems the number doubled 5 + 2(1) = 7 matches the coding; whereas with 'CHAIN', it has 4 consonants, hence: 'CHAIN' calculation 3(2)+1 gives 4, which matches the code.

Based on this logic, we have discovered another hypothesis of pattern where the code seems to be related to either a derivation but testing consonants hypothesis work in doubling.

4. Selecting the Correct Code for 'ADULTHOOD':
   • 'ADULTHOOD' has 5 vowels: A, U, O, O, O = 5 vowels.
   • It has 4 consonants: D, L, T, H = 4 consonants and doubling 4 is 8, it seems pattern of the logic to double to code gives 5 + 8
   • Thus, 'ADULTHOOD' is coded as '8'.

This final solution strategy allows us to conclude that the word 'ADULTHOOD' will be coded as '8' based on the pattern deduced about using consonants and complicated pattern.