The term 'strange quality' can be summed up by the 8-letter word 'eeriness'. Eeriness is an adjective that describes something as being mysterious, creepy, or unsettling. It is often used to describe a feeling or atmosphere, such as a dark and spooky forest or a haunted house. It can also be used to describe a person's behavior or mannerisms, such as someone who speaks in a strange and unsettling way.