An amorphous connect wall

Question

The set of sixteen items below can be partitioned. Each partition is of four items that have something in common. I invite you to figure out the partitions and commonalities. You'll find that the four commonalities are of the same type in some sense; and that, taken together, they clue an eight-letter word.

BULL, COME, DICK, KO, LEE, ME, MULL, NIT, RE-ROBE, RICH, RUBBLE, SEW, SHELLS, STIR, TELL, WEIGH

Hint (added later):

RE would work instead of RE-ROBE (and would be a more appropriate word for this puzzle) were it not for the fact that it's also a musical note. I included RE-ROBE because it's easy and in my hope that people use it to start solving the puzzle.

Another hint (added even later):

I don't know why I included NIT rather than KNIT. It makes no difference whatsoever.

Another hint (added even later):

LEE and TELL are in the same partition.

Another hint (mentioned a little while ago in the comments on the question):

Bubbler asked me whether the KO on the board is "ko" or "K.O." and I replied that it's the former and that that question is important.

Another hint (mentioned a little while ago in the comments on an answer):

The fact that none of the words contain the letter A is just by chance.

Well… there may actually be some sort of linguistic connection between the wall's rules and the absence of an A. Like, maybe it's easier to find non-A words to fit the wall's rules than to find A words to fit them. But knowing that is probably not going to help you.

Another hint (added even later):

One European and one African country are represented here by name.

Another hint (added even later):

Also, a big city in East Anglia is represented by name.

Answer 1

8 letter word:

Carreras thanks to JS1 for this

Group 1

Prefix Ho__+ word (LEE, TELL, COME, ME) makes Holy, Hotel, Hokum, Homey

Group 2

Prefix Nor__+ word (WEIGH, DICK, RICH, MULL) makes Norway, Nordic, Norwich, Normal

Group 3

Prefix Sey__+ word (SHELLS, SEW, BULL, KO) Seychelles, Say-So , Sable, Seiko

Group 4

Prefix Te + word (RE-ROBE, RUBBLE, STIR, NIT) Terry-Robe, Terrible, Tester, Tenet

If you take the syllables you can spell Jose Tenor which hints at Jose Carreras.

Answer 2

Firstly, there's something very important to notice about the word set in this puzzle:

None of the words contain the letter 'A'!

I believe this is a deliberate clue and is supposed to hint at:

The need to manipulate these words using the letter A to make new words. This is backed up by use of the word 'A-MORPHOUS' in the title, which suggests in a punny way that we need to morph (i.e. 'change the form of') the words in this puzzle using the letter 'A' in all of our transformations.

The wall can then be resolved as follows:

Group 1: Can add an 'A' to make a new word
BULL --> BULLA
LEE --> ALEE
STIR --> ASTIR/SATIR/STAIR
WEIGH --> AWEIGH

Group 2: Can change the last letter to an 'A' to make a new word
COME --> COMA
KO --> KA
ME --> MA
SEW --> SEA

Group 3: Change a letter other than the last to an 'A' to make a new word
REROBE --> AEROBE
RUBBLE --> RABBLE
SHELLS --> SHEALS
TELL --> TALL

Group 4: Change a letter to an 'A' and reverse the letter order to make a new word
DICK --> DICA --> ACID
MULL --> MULA --> ALUM
NIT --> NAT --> TAN
RICH --> RIAH --> HAIR

While I can't immediately spot a punny 8-letter word that sums this up, a suitable one based on earlier observations about the title might be:

MORPHING - although I am open to better suggestions!

Answer 3

First step is to make a wall. The words are in alphabetical order in the puzzle, and I am assuming they must be grouped an re-ordered.

3 or less
clue: "I don't know why I included NIT rather than KNIT"
answer: 3 rather than 4 letters, number of letters is important?
KO LEE ME NIT

have LL
BULL MULL SHELLS TELL

verbs that involve an object
RE-ROBE STIR SEW WEIGH

remainder
COME DICK RICH RUBBLE

Which creates a wall like - alphabetical

 BULL     MULL    SHELLS   TELL     
 COME     DICK    RICH     RUBBLE
 KO       LEE     ME       NIT   
 RE-ROBE  STIR    SEW      WEIGH   

Or perhaps grouped vertically

 BULL     COME    KO       RE-ROBE
 MULL     DICK    LEE      STIR
 SHELLS   RICH    ME       SEW
 TELL     RUBBLE  NIT      WEIGH

But the order of the elements in the wall is a mystery to me. Assuming the elements in the 4 groups are related to each other, than what order are the 4 groups to each other?