Without context, both "the book" and "a book" are reasonable translations.
Perhaps it hadn't been added to the database when you tried. It's there now (8 March 2020).
Why is the l in luvenis not being pronounced?
It's not an l (Lima), it's an I (India), and it is pronounced like Y as in "yes."
Why is it wrong to say 'a book' instead of 'the book'?