WordNet records no synonym and no antonym for shielding. 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.
a shield of lead or concrete intended as a barrier to radiation emitted in nuclear decay
shield consisting of an arrangement of metal mesh or plates designed to protect electronic equipment from ambient electromagnetic interference
Synonyms, antonyms and the broader and narrower relations for shielding come from Princeton University’s WordNet. Full sources and licences.