What Constitutes As "grave Matter?"

[MonjaFutura]

Does using a four-letter word just as a habit count as a mortal sin? And what does constitute as "grave matter" when it comes to sins?

[Theoketos]

You have two questions here. Lets work in reverse order but starting with a quote from the CCC 

 

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."¹³¹

 

1858 Grave matter is specified by the Ten Commandments, corresponding to the answer of Jesus to the rich young man: "Do not kill, Do not commit adultery, Do not steal, Do not bear false witness, Do not defraud, Honor your father and your mother."¹³² The gravity of sins is more or less great: murder is graver than theft. One must also take into account who is wronged: violence against parents is in itself graver than violence against a stranger.

 

1859 Mortal sin requires full knowledge and complete consent. It presupposes knowledge of the sinful character of the act, of its opposition to God's law. It also implies a consent sufficiently deliberate to be a personal choice. Feigned ignorance and hardness of heart¹³³ do not diminish, but rather increase, the voluntary character of a sin.

 

1860 Unintentional ignorance can diminish or even remove the imputability of a grave offense. But no one is deemed to be ignorant of the principles of the moral law, which are written in the conscience of every man. The promptings of feelings and passions can also diminish the voluntary and free character of the offense, as can external pressures or pathological disorders. Sin committed through malice, by deliberate choice of evil, is the gravest.

 

1861 Mortal sin is a radical possibility of human freedom, as is love itself. It results in the loss of charity and the privation of sanctifying grace, that is, of the state of grace. If it is not redeemed by repentance and God's forgiveness, it causes exclusion from Christ's kingdom and the eternal death of hell, for our freedom has the power to make choices for ever, with no turning back. However, although we can judge that an act is in itself a grave offense, we must entrust judgment of persons to the justice and mercy of God.

 

 

So grave matter refers to the objective damage the act (unknowingly or unwillingly) does. The damage is severe then the matter is grave. 

 

Although it is really dense, here is St. Thomas on what makes a sin mortal. It is from the first part of the second part of the summa in question 88 article 1. 

 

For sin, being a sickness of the soul, as stated above, is said to be mortal by comparison with a disease, which is said to be mortal, through causing an irreparable defect consisting in the corruption of a principle, as stated above . Now the principle of the spiritual life, which is a life in accord with virtue, is the order to the last end, as stated above: and if this order be corrupted, it cannot be repaired by any intrinsic principle, but by the power of God alone, as stated above, because disorders in things referred to the end, are repaired through the end, even as an error about conclusions can be repaired through the truth of the principles. Hence the defect of order to the last end cannot be repaired through something else as a higher principle, as neither can an error about principles. Wherefore such sins are called mortal, as being irreparable.

On the other hand, sins which imply a disorder in things referred to the end, the order to the end itself being preserved, are reparable. These sins are called venial: because a sin receives its acquittal [veniam] when the debt of punishment is taken away, and this ceases when the sin ceases, as explained above.

 

 

Now I cannot say for sure whether or not a four letter word out of habit is a mortal sin or not. It very well could be, but it probably is not. Habit diminishes the will. Most people are not scandalized by such language in our age, and some of those words have non scandalous or proper contexts. Cuss words (distinct from the blasphemy of cursing) do still cause scandal and do not reflect a proper stewardship of our tongues.  

I still recommend living beyond reproach in this matter. Speak only what is good true and beautiful. Edit out the media consumption in your life that uses this words, and you will find the habit easier to break.