but
...to understand what he means is all but impossible

difficult
...me to understand

give
to give to understand

given
I'm given to understand that...

hardly
she could hardly understand what he said

heart
...does not understand / the heart has reasons that reason does not recognize

pretend
don't pretend you don't understand

quite
I quite understand

to
that is easy to understand

understand
he was given to understand that...

understood
entendido