With the birth of their child, the attempts to feed it and the various failures in doing so, and with the real and imaginary illnesses of mother and child, in which Ivan Ilych’s sympathy was demanded but about which he understood nothing, the need of securing for himself an existence outside his family life became still more imperative.
There are no more uses of "imperative" in the book.
Show samples from other sources
I’m hoping to be able to reveal this to my father soon enough, but, for tonight, discretion is imperative."
Kiera Cass -- The One
The evolutionary imperative that drove them to live in groups was the opportunity to kill them by the billions.