This might be completely uninteresting to most people, but the Greek translation of the Hebrew Bible, called the Septuagint (LXX), avoided the common word for "uncle" (θείος) because it was also the common word for divine beings, and so they typically substituted the word οικεῖος, "family member, kinsman" (so 1 Sam 10:14,15,16; 14:50) or the phrase ὁ ἀδελφός τοῦ πατρός, "the brother of the father" (so 1 Chr 27:32 πατράδελφος, Est 2:15; Jer 32:7).
Far from being uninteresting, this could help learners to retain the different meanings of the nouns θείος & θεία and the adjective θείος, θεία, θείο.
In ancient Greek, there are five different words for uncle: θεῖος, πάτρως or πατράδελφος (for paternal uncle) and μήτρως or μητράδελφος (for maternal uncle). There is a similar pattern for aunt.
In modern Greek, we only have θείος and θεία. That said, the adjective θείος, α, ο is a synonym of θεϊκός, η, ό (= divine, godly), but it is mostly used in some fixed expressions, such as (η) Θεία Ευχαριστία (= Holy Communion).
I hope this helps. :-)