Some thoughts I have:
Quantum randomness seems aleatory, so anything that depends on that to a large extent (everything depends on that to some extent) would probably also fit the term.
Winter solstice / summer solstice? Popular secular holiday in EA circles (though not strictly EA per se)
In case someone has capacity to do this right now, I'm under the impression that Open Phil does want their own page (based on conversation I had with someone researching there).