Which term refers to the initial stage of existence or appearance?

The term that refers to the initial stage of existence or appearance is "incipient." This word specifically denotes something that is beginning to develop or come into being. It captures the essence of something that is in its early phases or not yet fully formed. The use of "incipient" often implies potential growth or evolution, emphasizing that the subject is at a nascent stage.

In contrast, "developed" and "established" refer to states that are advanced or mature, indicating a progress that has already been made from the initial stages. "Obscure" suggests something that is not clearly understood or is hidden, which doesn't align with the notion of beginning or initial appearance. Therefore, "incipient" is the most accurate term to describe something in its first stage of existence.