grave sin

Struggling with her emotion, thinking hardly at all of the grave sin which she had committed, Kitty sat down by her open window.

St. Alphonsus says if there is danger of abortion the use of the debitum is a grave sin.

We have come to two conclusions; to secede is a grave sin, but to lie is also a grave sin.

It were a sin, a grave sin, in a newly-made novice, cloister-bred.

On one occasion it was debated whether a clergyman who had five years before been guilty of some grave sin should be reinstated.