digest has 14 distinct synonyms spread across 3 of its 10 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. WordNet records no antonym for it — antonymy is a relation between word forms rather than concepts, so it is deliberately sparse.
Counts are distinct word forms across every sense. A synonym that appears under three senses is counted once here and shown three times below, under each sense it belongs to.
arrange and integrate in the mind
“I cannot digest all this information”
become assimilated into the body
“Protein digests in a few hours”
systematize, as by classifying and summarizing
“the government digested the entire law into a code”
soften or disintegrate, as by undergoing exposure to heat or moisture
make more concise
“condense the contents of a book into a summary”
soften or disintegrate by means of chemical action, heat, or moisture
a periodical that summarizes the news
something that is compiled (as into a single book or file)
Synonyms, antonyms and the broader and narrower relations for digest come from Princeton University’s WordNet. Full sources and licences.