WordNet records no synonym and no antonym for orphan. It is the only member of each of its synsets, which is common for technical, taxonomic and single-sense vocabulary — there is no other English word that means the same thing. The broader and narrower terms below are the useful relations in that case.
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.
someone or something who lacks support or care or supervision
the first line of a paragraph that is set as the last line of a page or column
Synonyms, antonyms and the broader and narrower relations for orphan come from Princeton University’s WordNet. Full sources and licences.