Maybe we use these terms differently in different domains. In my field, stochastic means that repeating the same experiment under the same conditions doesn't guarantee the same results (e.g. rolling a die). The opposite of stochastic is deterministic. Something that changes depending on the day would be "a function of the date" or something that is "conditional on the date". This can either be a deterministic function (e.g. calling date.today().day in Python, or a mapping from the date to a uniform distribution ranging from 0 to date.today().day) or a stochastic function (e.g. sample a uniform random integer between 0 and date.today().day).

Edit: I think what you're talking about is the deterministic mapping from some variable into a distribution. We (as in my field specifically) do sometimes call that "stochastic" too, even though that mapping is deterministic. There may be a bit of terminology overloading here because what we care about in the end is the sample drawn from that distribution, which is actually stochastic.