Suggest, adumbrate, shadow are comparable when they are predicated of things that serve indirectly to represent another thing because they evoke a thought, an image, or a conception of it.
One thing suggests another when it brings to mind something that is not objectively present, immediately apparent, or directly represented. The thing that suggests may be an outward sign which prompts an inference. It may be a symbol, which calls to mind whatever it conventionally represents. It may be a fragment which evokes an image of a whole or a concrete detail that gives an inkling of something abstract or incapable of representation. It may be a word or a phrase that calls up a train of associations and reveals more than it actually denotes.
One thing adumbrates another when the former faintly or darkly or sketchily suggests the latter. Adumbrate seldom takes a material object and is especially appropriate for use with one that is or is felt as beyond the present level or sometimes the reach of human comprehension or imagination.
When one thing shadows (or shadows forth ) another thing, it represents that thing obscurely (as by a symbol or other indirect means).
Sometimes the word comes close to prefigure or foreshadow , but as a rule precedence is not implied.