What is a Mutated Word™?

This is in the spirit of the What is a Word™/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles.

If a word conforms to a special rule, I call it a Mutated Word™.
Use the examples below to find the rule.

Mutated Words™ Not Mutated Words™
BRASH CALM
CROWN TIARA
DINNER LUNCH
FEEL SENSE
SEAT STOOL
SUPPER BREAKFAST
THINK REACT
WHOSE WHOM

In case you want it in CSV:

Mutated Words™,Not Mutated Words™
BRASH,CALM
CROWN,TIARA
DINNER,LUNCH
FEEL,SENSE
SEAT,STOOL
SUPPER,BREAKFAST
THINK,REACT
WHOSE,WHOM


The puzzle relies on the series' inbuilt assumption, that each word can be tested for whether it is a Mutated Word™ without relying on the other words.

These are not the only examples of Mutated Words™, many more exist.

• That chair is bugging me Jan 26, 2017 at 19:56
• Actually, now that I look at it, chair is a mutated word. I will update. Jan 26, 2017 at 20:39
• Is stool a mutated word also? Jan 26, 2017 at 23:30

My guess would be that

a mutated word is a word that is created by combining 2 other words with some cross over (specifically the second word starts with the second last letter of the first word)

Explanations:

BRA and RASH --> BRASH
CROW and OWN --> CROWN
DIN and INNER --> DINNER
FEE and EEL --> FEEL
SEA and EAT --> SEAT
SUP and UPPER --> SUPPER
THIN and INK --> THINK
WHO and HOSE --> WHOSE

Similarly a non mutated word is any word that doesn't fit that condition

Ex. BREAKFAST --> BREAK and FAST do not cross over

• @MikeQ AIR also works for that though. Either way, it fits for all the ones in the actual question Jan 26, 2017 at 21:03
• Yeah, basically any two words that share two letters. So, CHAIR IS CHAI and AIR. Your explanation of the "second last letter" was spot on. Jan 27, 2017 at 17:44

Can be reduced letter by letter to a single letter word leaving an (albeit archaic or obscure) word at each stage.

E.g. brash->rash->ash->as->a think->hink->ink->in->I

But obviously not the answer: whom->who->ho->o stool->tool->too->to->o

• How do you do that with FEEL? (Also, welcome to Puzzling!)
– Deusovi
Jan 27, 2017 at 3:10
• @Deusovi Feel-eel-el-e where el is a unit of measurement and E is the 3rd degree of the C-major scale Jan 27, 2017 at 3:14
• Yeah, doesn't work with both sets of answers, but I like this reasoning. Would probably make a great "What is a Word" puzzle down the road once people forget about it. Jan 27, 2017 at 18:10

A Mutated Word™ is a word that:

remain a word after removing the first letter

Example:

BRASH -> RASH
CROWN -> ROWN
DINNER -> INNER

Not Mutated:

CALM -> ALM
TIARA -> IARA

• Stool -> tool. That one doesn't work
– Nik
Jan 26, 2017 at 22:21
• And Calm -> Alm works. But Whom -> Hom,Think -> Hink, and Crown -> Rown do not. Jan 27, 2017 at 18:12