All the words below share an unusual property. Can you determine what it is?

BRAWL

CHANGE

CLOVER

PROPER

STONE

SEVENTY

SWING

TRAVEL

 

Answer:

 

If you drop the first and last letters of each word, a valid word remains:

 

BRAWL - RAW

CHANGE - HANG

CLOVER - LOVE

PROPER - ROPE

STONE - ONE

SEVENTY - EVENT

SWING - WIN

TRAVEL - RAVE