This puzzle 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 Counterfeiting word™. Here are some examples of Counterfeiting word™ and not Counterfeiting word™:
+----------------------+--------------------------+
| Counterfeiting Word™ | not Counterfeiting Word™ |
+----------------------+--------------------------+
| push | first |
| fast | strong |
| noisy | light |
| defend | against |
| old | floor |
| adult | refuse |
| wet | wide |
| major | exit |
| wrong | correct |
| export | buy |
| below | optimistic |
| failure | all |
| lose | girl |
| soft | expensive |
| include | hot |
| senior | ascent |
| permit | happy |
+----------------------+--------------------------+
And a CSV version for copy-paste purpose:
Counterfeiting Word™,not Counterfeiting Word™
push,first
fast,strong
noisy,light
defend,against
old,floor
adult,refuse
wet,wide
major,exit
wrong,correct
export,buy
below,optimistic
failure,all
lose,girl
soft,expensive
include,hot
senior,ascent
permit,happy
You can check whether a word is a Counterfeiting word™ or not without looking at the words in its column. These are not the only Counterfeiting words™: many more exist.