What do the following three-letter words have in common?

FUR
IMP
COP
CUR
TED
DUB

HINT:
The same three letters will change each word into a new one.

Answer:

Each word can be changed into a new one by adding IOUS at the end:

FURIOUS
IMPIOUS
COPIOUS
CURIOUS
TEDIOUS
DUBIOUS 

Credit:
GAMES/World of Puzzles
September, 2018
DEBT RECKONING