During the synthesis stage of the cell cycle, a cell makes (replicates its own) DNA.
Economic profits equals total revenues minus the sum of explicit costs and implicit costs. Since explicit costs are already subtracted when arriving at the accounting profit, we can find economic profit by subtracting the implicit costs from the accounting profit.
The opportunity cost of an activity. Implicit costs are what a company or individual could have earned had a different decision been made. For example, suppose an independent consultant has two clients and she spends some time working on the first client's project.