Hubris is a Greek term that means excessive/deadly pride or arrogance before the gods. She is also a personified daemon. Soon after one succumbs to Hubris, Nemesis enacts retribution.
Since hubris is such a bad thing, did the Greeks have a term opposite of it?
The opposite of Hubris is Sophrosyne (σωφροσύνη). It is considered an important quality to have and is expressed in opposition to the concept of hubris. The meaning of the concept Sophrosyne is, "an ideal of excellence of character and soundness of mind." No language has an equal word to Sophrosyne.
When one has Sophrosyne, it leads to other qualities of humble importance. Qualities are such: temperance, moderation, prudence, purity, and self-control.
The word Sophrosyne was used in Plato's writing and my have been influenced by Heraclitus. His fragment 112 states, "Sophrosyne is the greatest virtue, and wisdom is speaking and acting the trust, paying heed to the nature of things."
Sophrosyne is also a personified daemon. She was released from Pandora's jar and left the cosmos on her way to Olympus.
Following E.R. Dodds' (1951) The Greeks and the Irrational, I'd suggest that @Andrew Johnson and @DukeZhou are both correct, in a way.
Among the Ancient Greeks, Greek sōphrosynē ("moderation," "temperance") was sometimes considered to be the opposite of Greek hybris, English "hubris." Among the Christians, however, Dodd's suggested the opposite of hybris/hubris was "humility" (Latin: humilitas; Greek: tapeinós).
(As two asides, in Ancient Greek, tapeinós often meant "debased," "dejected," "low-lying," even "bad" in the sense of "debased". And, technically speaking, the opposite of sōphrosynē is often considered by etymologists to be represented by the Greek word mania: "madness.")
