The eponymous character of Euthyphro suggests that the definition of piety is that which is loved by the gods and, should gods disagree, that which is loved by all the gods.
Socrates points out that things must be pious before the gods could love them but nothing can be loved by the gods or anyone else until after it is loved. There’s no “Euthyphro dilemma” as usually understood here, but only a logical point: it’s not as if the gods could approve of your sacrifice before you offered it or that something could be loved before someone loved it.
If we stopped reading the dialogue here we might raise the question why the pious was not what is loved by the gods, but we couldn’t very well suggest that the gods are superfluous to the nature of piety, in the way that the “Euthypho dilemma” suggests that God is wholly superfluous to the nature of the moral good. The whole question of piety is how the gods are essential to it, not whether they are.
There is also no question that Socrates takes piety as integral to human goodness, since he offers a partial definition of piety as a part of justice, and the Socratic understanding of justice is clear from Republic. Rather than asking questions about justice (since he never asks questions about anything) Euthyphro leaps into trying to figure out what makes piety different from justice and be bungles the question badly, but here too his mistakes are instructive. Ultimately Euthypho conceives of piety as benefiting the gods, when in fact piety is a part of justice because the nature of the gods demands that we perfect ourselves by becoming more cognizant of them, through the elevation of the mind and discipline of the body that recognizes that all physical goods come from a non-physical source, that this spirit deserves our praise and gratitude, and that we become ennobled by recognizing it as the measure of all that is noble, elevated, true and good. Doing this in the way most appropriate to our embodied state is piety.
Just Thomism 