" There's is this word. Nothing like it exists in the English language. It's Portuguese. Saudade. Do you know that one? It's more ... there's no perfect definition. It's more of an expression of feeling-of terrible sadness. It's the feeling you get when you realize something you once lost is lost forever, and you can never get it back again. "

― Alexandra Bracken , The Darkest Minds (The Darkest Minds, #1)