What is an HTM Word™?

In the spirit of the What is a Word™/Phrase™ series started by JLee

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

$$% set Title text. (spaces around the text ARE important; do not remove.) % increase Pad value only if your entries are longer than the title bar. % \def\Pad{\P{0.0}} \def\Title{\textbf{ HTM }} % \def\S#1#2{\Space{#1}{20px}{#2px}}\def\P#1{\V{#1em}}\def\V#1{\S{#1}{9}} \def\T{\Title\textbf{Words}^{\;\!™}\Pad}\def\NT{\Pad\textbf{Not}\T\ } \smash{\lower{29px}\bbox[teal]{\phantom{\rlap{rubio.2019.05.15}\S{6px}{0} \begin{array}{cc}\Pad\T&\NT\\\end{array}}}}\atop\def\V#1{\S{#1}{5}} \begin{array}{|c|c|}\hline\Pad\T&\NT\\\hline % \text{ navajo}&\text{ apache}\\ \hline \text{ beefburger}&\text{ vowelburger}\\ \hline \text{ histogram}&\text{ bar chart}\\ \hline \text{ triumphal}&\text{ victorious}\\ \hline \text{ dynamite}&\text{ nitroglycerine}\\ \hline \text{ Ramanujan}&\text{ Newton}\\ \hline \text{ hallelujah}&\text{ suzanne}\\ \hline \text{ regular}&\text{ extraordinary}\\ \hline \text{ bumpers}&\text{ buffers}\\ \hline \text{ patchwork}&\text{ agricola}\\ \hline \text{ television}&\text{ radio}\\ \hline \text{ interconnected}&\text{ separated}\\ \hline \hline \end{array}$$

The CSV version:

HTM Words™,Not HTM Words™
navajo,apache
beefburger,vowelburger
histogram,bar chart
triumphal,victorious
dynamite,nitroglycerine
Ramanujan,Newton
hallelujah,suzanne
regular,extraordinary
bumpers,buffers
patchwork,agricola
interconnected,separated


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

What is the special rule these words conform to?

Hint:

there are 12 examples.

• This seems like a really challenging puzzle; I and some others have been thinking on it for a week with no success. Would you consider adding a hint? – chrylis -cautiouslyoptimistic- Mar 31 '20 at 6:51
• @chrylis-onstrike- Fun fact: I was going to post the solution this afternoon. But since you have asked, I'll add an hint – melfnt Mar 31 '20 at 8:47
• @chrylis-onstrike- as usual one "little" hint after makes someone easily find the right answer after a week. Is there any kind of "weaker" hint that I could have written to make the puzzle not-so-obvious? – melfnt Mar 31 '20 at 9:19
• I'm not sure (but keep in mind we've been looking at it for some time)! – chrylis -cautiouslyoptimistic- Mar 31 '20 at 10:28

An HTM Word is one which:

Contains a 3-letter month abbreviation sequentially among its letters when the word is spelled in reverse.

Like so:

navajo = NavAJo (JAN);
beefburger = BeEFburger (FEB);
histogram = histogRAM (MAR);
triumphal = tRiumPhAl (APR);
dynamite = dYnAMite (MAY);
Ramanujan = ramaNUJan (JUN);
hallelujah = halleLUJah (JUL);
regular = reGUlAr (AUG);
bumpers = bumPErS (SEP);
patchwork = paTChwOrk (OCT);
television = teleVisiON (NOV);
interconnected = interConnectED (DEC).

As for the name:

'HTM' is a 3-letter abbreviation for 'month' (i.e. MTH) in reverse!

• Almost true, except for one little detail: the not-HTM word rot13(frcnengrq) respects your criterion – melfnt Mar 31 '20 at 9:23
• @melfnt I don't think it does - that only has it forwards in the first 3 letters doesn't it? EDIT: I have altered the wording of my first spoiler in an attempt to add clarity - I suspect this is purely linguistics... :) – Stiv Mar 31 '20 at 9:37
• it "has all the letters" as of your previous wordings. You need to add the order constraint (which you did) otherwise your definition does not work. Well done anyway! – melfnt Mar 31 '20 at 10:41