From Living for God's Glory, by Joel Beeke:
In defining irresistible grace, let us first look at the term grace, then focus on the adjective. The Old Testament Hebrew term for grace and its derivatives suggests kindness, favor, and graciousness. The New Testament Greek term suggests goodwill, lovingkindness, and favor. When applied to sinful men in a redemptive context, grace means unmerited favor in the place of merited wrath. Too often, grace is defined only as God's unmerited favor to sinners. The word unmerited, however, is took weak. As sinners, we have de-merited God's favor. Not only do we not deserve grace, we do deserve hell. Grace is God's blessing freely bestowed on ill-deserving sinners. It is a blessing bestowed at the cost of Christ's sufferings and death. Grace is God's love in Christ put into action. Grace is mightier than all our sins, our adverse circumstances, and our human impossibilites. Grace is the heart of the Bilble and our salvation.