In the spirit of the What is a Word™/Phrase™ series started by JLee, a special brand of Phrase™ and Word™ puzzles.
If a word conforms to a special rule, I call it a Headered Word™.
Use the examples below to find the rule.
$$ % set Title text. (spaces around the text ARE important; do not remove.) % increase Pad value only if your entries are longer than the title bar. % \def\Pad{\P{1.2}} \def\Title{\textbf{ Headered }} % \def\S#1#2{\Space{#1}{20px}{#2px}}\def\P#1{\V{#1em}}\ \def\V#1{\S{#1}{9}} \def\T{\Title\textbf{Words }^™\Pad}\def\NT{\Pad\textbf{Not}\T\ }\displaystyle \smash{\lower{29px}\bbox[yellow]{\phantom{\rlap{rubio.2017.02.04}\S{6px}{0} \begin{array}{cc}\Pad\T&\NT\\\end{array}}}}\atop\def\V#1{\S{#1}{5}} \begin{array}{|c|c|}\hline\Pad\T&\NT\\\hline % \text{ A* }&\text{ AN }\\ \hline \text{ ADDLE }&\text{ ADDLED }\\ \hline \text{ ADORE }&\text{ ADORABLE }\\ \hline \text{ ADULT }&\text{ ADOLESCENT }\\ \hline \text{ BABY }&\text{ CHILD }\\ \hline \text{ BE* }&\text{ BEE }\\ \hline \text{ BLEMISH }&\text{ BLISTER }\\ \hline \text{ BOA }&\text{ BOW }\\ \hline \text{ BREATHE }&\text{ BREATH }\\ \hline \text{ CANDLES }&\text{ CANDLE }\\ \hline \text{ DIFFERENT }&\text{ DIFFER }\\ \hline \text{ EVERY* }&\text{ EACH }\\ \hline \text{ FAVORABLENESS }&\text{ FAVOR }\\ \hline \text{ FAVOURABLENESS }&\text{ FLAVOUR }\\ \hline \text{ FRIEND* }&\text{ FIEND }\\ \hline \text{ HEADERED* }&\text{ HEADER }\\ \hline \text{ ILLEGIBLE* }&\text{ LEGIBLE }\\ \hline \text{ MISCLASSIFIED* }&\text{ MAYBE }\\ \hline \text{ MULTISYLLABIC* }&\text{ MULTIPLE }\\ \hline \text{ MEASURABILITY* }&\text{ MEASURED }\\ \hline \text{ PRESUPPOSITIONAL*}&\text{ PARTITIONS }\\ \hline \end{array}$$ *Single-Headered Words
And, if you want to analyze, here is a CSV version:
Headered Words™,Not Headered Words™
A,AN
ADDLE,ADDLED
ADORE,ADORABLE
ADULT,ADOLESCENT
BABY,CHILD
BE,BEE
BLEMISH,BLISTER
BOA,BOW
BREATHE,BREATH
CANDLES,CANDLE
DIFFERENT,DIFFER
EVERY,EACH
FAVORABLENESS,FAVOR
FAVOURABLENESS,FLAVOUR
FRIEND,FIEND
HEADERED,HEADER
ILLEGIBLE,LEGIBLE
MISCLASSIFIED,MAYBE
MULTISYLLABIC,MULTIPLE
MEASURABILITY,MEASURED
PRESUPPOSITIONAL,PARTITIONS
The puzzle satisfies the series' inbuilt assumption, that each word can be tested for whether it is a Headered Word™ without relying on the other words.
These are not the only examples of Headered Words™; many more exist.
What is the special rule these words conform to?
Bonus Headered Word™, which is maybe the longest Headered Word™:
FLOCCINAUCINIHILIPILIFICATION
Update 08/11
Marked Single-Headered Words™
2nd** Hint 08/18
**the Single-Headered Words™ didn't count as a hint
As a consequence of the property of Headered Words™, they also have the following property:
Concatenating two Headered Words™ will make a Headered Word™, assuming the result is a word.
e.g. BEFRIEND is a Headered Word™ because both BE and FRIEND are Headered Words™.
This does not necessarily mean that removing a Headered Word™ from a longer Headered Word™ will result in a second short Headered Word™.