I read from deuteranope to devaluation.

Deuterium is heavy hydrogen:

https://en.wikipedia.org/wiki/Deuterium

Deuteronomy means "second law"!

https://en.wikipedia.org/wiki/Book_of_Deuteronomy

Deuterostomes are named that because their anus is their second mouth. Really!

Well, not really.  It just means that the anus forms before the mouth, but it does mean "second mouth"!

https://en.wikipedia.org/wiki/Deuterostome

Before the Deutsch ...