[narses]

You are close.

1857 For a sin to be mortal, three conditions must together be met: ‘Mortal sin is sin whose object is grave matter and which is also committed with full knowledge and deliberate consent.’

The usual conditions are thus:

Grave matter
Full knowledge
Deliberate consent

[JMJ333]

[NYer]

Thanks, narses, for properly rephrasing the conditions. Amazing, though, the impact those nuns had on us in elementary school.