This requires a yes and a no answer to the question of if there is a “Once Saved Always Saved” premise in the Bible.
For the yes answer.
For I am persuaded, that neither death, nor life, nor angels, nor principalities, nor powers, nor things present, nor things to come, Nor height, nor depth, nor any other creature, shall be able to separate us from the love of God, which is in Christ Jesus our Lord. Romans 8:38-39
We are to be secure in our salvation. Nothing can separate us from Christ, it is guaranteed to us. Thus when we accept Christ, we are guaranteed salvation.
Who are kept by the power of God through faith unto salvation ready to be revealed in the last time. 1Peter 1:5
This is also another text which allows us to be secure in our salvation. For God Himself keeps us close through faith.
Now for the no answer.
We ourselves can denounce Christ. We can push away the Holy Spirit and thus our salvation.
I was a stranger, and ye took me not in: naked, and ye clothed me not: sick, and in prison, and ye visited me not. Then shall they also answer him, saying, Lord, when saw we thee an hungred, or athirst, or a stranger, or naked, or sick, or in prison, and did not minister unto thee? Then shall he answer them, saying, Verily I say unto you, Inasmuch as ye did it not to one of the least of these, ye did it not to me. Matt 25:42-45
And he spake many things unto them in parables, saying, Behold, a sower went forth to sow; And when he sowed, some seeds fell by the way side, and the fowls came and devoured them up: Some fell upon stony places, where they had not much earth: and forthwith they sprung up, because they had no deepness of earth: And when the sun was up, they were scorched; and because they had no root, they withered away. And some fell among thorns; and the thorns sprung up, and choked them: But other fell into good ground, and brought forth fruit, some an hundredfold, some sixtyfold, some thirtyfold. Matt 13:3-8
Like the above texts tell us, there will be those who are lost. God calls us to show Christ to the world, if we fail to do that Christ will fail to recognize us. The parable of the sower is to warn us about taking our salvation lightly. As a Christian we are married to Christ and must take our wedding vows seriously. So in the definition that you have of OSAS, these texts refute that belief, and there are other texts but I will allow you to look them up.
So a brief recap, we cannot have salvation torn from us, but we can give it up of our own free will.