This is the 9288th most frequent Portuguese word.
caído
"Caído" in English means "fallen."
Here, 'caído' is used as a past participle to indicate the state of the book after having fallen.
O livro está caído no chão.
The book is fallen on the ground.
In this context, 'caído' is used metaphorically to describe someone feeling emotionally down or depressed.
Ele parecia muito caído após ouvir as notícias.
He seemed very down after hearing the news.
'Caído' is again used as a past participle describing the physical state of the branches after succumbing to the snow's weight.