The two words in each pair below are related in a certain way. Can you determine what it is?

COUP - PARTNER
DAMN - NIGHT
MNEMONIC - MOVIE
LISTEN - TREATMENT
ISLAND - SPRING

HINT:
It has to do with silent letters.

Answer:

The first word in each clue pair has a silent letter. That silent letter is the first letter of the second word in the pair, but it is no longer silent. The second word can be preceded by the word "silent."

COUP - SILENT PARTNER
DAMN - SILENT NIGHT
MNEMONIC - SILENT MOVIE
LISTEN - SILENT TREATMENT
ISLAND - SILENT SPRING  (pioneering environmental book by Rachel Carson) 

Credit: NY Times Crossword
John Guzzetta - July 10, 2014