Inchoate means just beginning to form. You can have an inchoate idea, like the earliest flickers of images for your masterpiece, or an inchoate feeling, like your inchoate sense of annoyance toward your sister's new talking parrot.
Inchoate comes from a Latin word for beginning. When something is inchoate, although you don’t yet understand what it is fully, you have a strong sense that it is indeed coming. It’s stronger than the wisp of an idea that never turns into anything. But it’s hard to really find the language to describe an inchoate idea. That’s the whole point: you don’t have the words for it yet!