What does it mean that Christ is the end of the Law?

Does nomos (Greek for law in Rom 2:14-15) mean the mosaic law or the law of Christ or natural or divine law or something else?

I am specifically interested in how to interpret this alongside Matt 5:18 "not one iota or dot will pass from the law until everything is accomplished." 

Romans 2:14 - 15

ESV - ¹⁴ For when Gentiles, who do not have the law, by nature do what the law requires, they are a law to themselves, even though they do not have the law. ¹⁵ They show that the work of the law is written on their hearts, while their conscience also bears witness, and their conflicting thoughts accuse or even excuse them

Clarify • Share • Report • Asked March 12 2016 • scot devlin