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 has a certain property, I call it an Emotional Word™. If it definitively does not have that property, it is an Emotionless Word™.
You can use the examples below to find the property:
$$\begin{array}{|c|c|} \hline \textbf{Emotional Word™}&\textbf{Emotionless Word™}\\ \hline \text{HOLIDAYS}&\text{VACATIONS}\\ \hline \text{MEN}&\text{WOMEN}\\ \hline \text{ MIXED*}&\text{JUMBLED}\\ \hline \text{SACK}&\text{BAG}\\ \hline \text{FAST}&\text{SPEEDY}\\ \hline \text{BIRDS}&\text{AVIANS}\\ \hline \text{HOUR}&\text{SECOND}\\ \hline \text{TRIGGER}&\text{EXPLOSION}\\ \hline \text{STRAIGHT}&\text{CURVED}\\ \hline \text{STIFF}&\text{FIRM}\\ \hline \end{array} $$ $$\text{* Meta-Emotional Word™.}$$
And a CSV version:
HOLIDAYS, VACATIONS
MEN, WOMEN
MIXED*, JUMBLED
SACK, BAG
FAST, SPEEDY
BIRDS, AVIANS
HOUR, SECOND
TRIGGER, EXPLOSION
STRAIGHT, CURVED
STIFF, FIRM
* Meta-Emotional Word™