triune
Both trine and one at the same time.
Christians believe in a triune God, meaning that he is three hypostases in perfect unity.
Of an artistic or literary work composed of three parts united by a single theme.
And, with that end, Zeus reëmerges as the divine protagonist of the triune drama.
Where it comes from
Borrowed from New Latin triūnus.
Adapted from the Wiktionary entry triune (CC BY-SA 4.0).