WordNet records no synonym and no antonym for comfort zone. 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.
the temperature range (between 28 and 30 degrees Centigrade) at which the naked human body is able to maintain a heat balance without shivering or sweating
Synonyms, antonyms and the broader and narrower relations for comfort zone come from Princeton University’s WordNet. Full sources and licences.