natural has 8 distinct synonyms spread across 6 of its 13 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. Its 5 recorded opposites are unnatural, artificial, supernatural, sharp, flat.
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.
in accordance with nature; relating to or concerning nature
“a very natural development”
existing in or produced by nature; not artificial or imitation
“a natural pearl”
existing in or in conformity with nature or the observable world; neither supernatural nor magical
“a perfectly natural explanation”
unthinking; prompted by (or as if by) instinct
“a cat's natural aversion to water”
1 of the 13 recorded senses carries no synonym, antonym or related term, so it is not shown above. Every sense, with its definition and examples, is on the full entry for natural.
Synonyms, antonyms and the broader and narrower relations for natural come from Princeton University’s WordNet. Full sources and licences.