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 Thanos Word™.
Use the following examples below to find the rule.
$$ % set Title text. (spaces around the text ARE important; do not remove.) % increase Pad value only if your entries are longer than the title bar. % \def\Pad{\P{1}} \def\Title{\textbf{ Thanos }} % \def\S#1#2{\Space{#1}{20px}{#2px}}\def\P#1{\V{#1em}}\def\V#1{\S{#1}{9}} \def\T{\Title\textbf{Words}^{\;\!™}\Pad}\def\NT{\Pad\textbf{Not}\T\ }\displaystyle \smash{\lower{29px}\bbox[yellow]{\phantom{\rlap{rubio.2019.05.15}\S{6px}{0} \begin{array}{cc}\Pad\T&\NT\\\end{array}}}}\atop\def\V#1{\S{#1}{5}} \begin{array}{|c|c|}\hline\Pad\T&\NT\\\hline % \text{ BLACK }&\text{ WHITE }\\ \hline \text{ BLINDSIDE }&\text{ IMPACT }\\ \hline \text{ DISCOMBOBULATED }&\text{ AWARE }\\ \hline \text{ FLIBBERTIGIBBET }&\text{ THINGAMAJIG }\\ \hline \text{ FLOTSAM }&\text{ DEBRIS }\\ \hline \text{ FOOLHARDY }&\text{ SAVVY }\\ \hline \text{ INTERLOPER }&\text{ GUEST }\\ \hline \text{ MASTERMIND }&\text{ NOVICE }\\ \hline \text{ NIGER }&\text{ NIGERIA }\\ \hline \text{ WHOOP }&\text{ BOO }\\ \hline \end{array}$$
And, if you want to analyze, here is a CSV version:
Thanos Words™,Not Thanos Words™
BLACK, WHITE
BLINDSIDE, IMPACT
DISCOMBOBULATED, AWARE
FLIBBERTIGIBBET, THINGAMAJIG
FLOTSAM, DEBRIS
FOOLHARDY, SAVVY
INTERLOPER, GUEST
MASTERMIND, NOVICE
NIGER, NIGERIA
WHOOP, BOO
Hint 1: