Attribute by which God, perfectly and eternally, knows everything that can be known: past, present and future. God knows how best to accomplish his ends. The Bible clearly teaches the omniscience of God (Psa 147:5; Pro 15:11; Isa 46:10).
Source: Hispanic World Bible Dictionary
Divine attribute by which we think that God knows all things, present, past and future. We identify it with his infinite Wisdom and with his essential and total Intelligence.
In some aspects of this, and of other attributes, we find difficulties which have given rise to persistent interpretations among theologians.
For example, how is it possible that God knows in advance whether a man is going to be saved or damned (divine foreknowledge) and that human freedom to be damned if he voluntarily does evil or to be saved if he chooses good is preserved. From the human perspective this aspect can never be clarified, as it is mysterious. But from the divine perspective it does not offer any problem, if we take into account that for God there is neither before nor after, but that he is always continuously present.
When those being catechized insist on elucidating these anthropocentric questions, it is good to tell them that God knows things because they are going to happen and not that they are going to happen because God knows them. But that God has made man free, and more than arguing about the consequences of freedom, the important thing is to live well and make the most of it.
Pedro Chico González, Dictionary of Catechesis and Religious Pedagogy, Editorial Bruño, Lima, Peru 2006
Source: Dictionary of Catechesis and Religious Pedagogy
see Knowledge of God.
Source: Dictionary of Theology