Pronunciation: /ə kloʊzd bʊk/
noun a word that represents a person, place, thing, or idea
A1 For me, math is a closed book.
A2 She finds technology to be a closed book.
B1 Learning a new language can be a closed book for some people.
B2 The topic of quantum physics remains a closed book to many.
C1 Despite years of study, advanced calculus is still a closed book to him.
C2 Even for experts in the field, the workings of the human brain can be a closed book.
adjective a word that describes or modifies a noun
A1 To me, advanced calculus is a closed book.
A2 For many people, quantum physics is a closed book.
B1 Her emotions are often a closed book to others.
B2 The intricacies of international law remain a closed book to most people.
C1 The inner workings of the stock market are a closed book to many investors.
C2 To the average person, the complexities of string theory are a closed book.
article a word that is used to specify a noun as definite or indefinite
A1 For some people, math is a closed book.
A2 To me, chemistry is a closed book.
B1 The topic of quantum physics is a closed book to most high school students.
B2 Despite my efforts, understanding advanced calculus remains a closed book to me.
C1 Even after years of studying, the intricacies of astrophysics are still a closed book to me.
C2 The complexities of string theory continue to be a closed book even to seasoned physicists.
formal Her research methods were like a closed book to me.
informal I don't understand calculus at all, it's like a closed book to me.
slang Physics is a closed book for me, I just can't get it.
figurative His emotions are like a closed book, I can never tell what he's thinking.
was a closed book
closed books
more closed book
most closed book
is a closed book
will be a closed book
has been a closed book
is being a closed book
a closed book
closed book
to be a closed book
being a closed book
closed booked