Use 'adumbrate' when you want to describe a plan or idea without giving away every detail. In the meeting, she adumbrated the company's vision for the next year.
Pro Tip 2/3
Initial Thoughts
Use it to introduce the initial stages or thoughts about a complex subject. The lecture adumbrated the history of the Renaissance but didn't cover it all.
Pro Tip 3/3
Not a Summary
'Adumbrate' conveys a sense of beginning to describe, not summarizing the whole. He adumbrated the novel's themes without giving an entire summary.