WordNet records no synonym and no antonym for search warrant. It is the only member of its synset, 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.
a warrant authorizing law enforcement officials to search for objects or people involved in the commission of a crime and to produce them in court; the warrant describes the locations where the officials may search
Synonyms, antonyms and the broader and narrower relations for search warrant come from Princeton University’s WordNet. Full sources and licences.