Where does this definition of closed book come from?
This entry for closed book is sourced from GetWord Corpus, one of the dictionaries and corpora merged into Lughet.
Is closed book a noun, verb, or something else?
In this entry, closed book is tagged as 2n..
What is Lughet?
Lughet is a free trilingual dictionary covering nearly five million entries across Uyghur, Chinese, and English, drawn from more than ten source dictionaries and corpora.