Romans 5:12-21 makes it fairly clear:
"Therefore, just as sin came into the world through one man, and death through sin, and so death spread to all men because all sinned— for sin indeed was in the world before the law was given, but sin is not counted where there is no law. Yet death reigned from Adam to Moses, even over those whose sinning was not like the transgression of Adam, who was a type of the one who was to come.
But the free gift is not like the trespass. For if many died through one man’s trespass, much more have the grace of God and the free gift by the grace of that one man Jesus Christ abounded for many. And the free gift is not like the result of that one man’s sin. For the judgment following one trespass brought condemnation, but the free gift following many trespasses brought justification. For if, because of one man’s trespass, death reigned through that one man, much more will those who receive the abundance of grace and the free gift of righteousness reign in life through the one man Jesus Christ.
18 Therefore, as one trespass led to condemnation for all men, so one act of righteousness leads to justification and life for fall men. For as by the one man’s disobedience the many were made sinners, so by the one man’s obedience the many will be made righteous. Now the law came in to increase the trespass, but where sin increased, grace abounded all the more, so that, as sin reigned in death, grace also might reign through righteousness leading to eternal life through Jesus Christ our Lord."
Paul is saying that through Adam's disobedience, the many were made sinners. What this means is that God invoiced every descendant of Adam with the debt of sin. God made them sinners until the debt was paid. This is why Jesus, just before He died on the Cross, said, "It is finished", the Aramaic meaning, "The debt is paid". Jesus paid the debt of sin owing by every person, but the condition of it being made active was that the person needed to put their trust in Christ, repent of their sin, and allow the Holy Spirit to convert them to Christ. As a result, the righteousness of Christ is credited to the person. The file is stamped, "Paid in full."
Paul says that even if people sin in ways different to how Adam sinned, they are still counted as sinners by God's decree. So, the only way that the decree can be cancelled is through repentance of sin and faith in Christ. The word "imputed" may not have been used, but the meaning is still there in the Romans passage.