WordNet records no synonym and no antonym for ironing. 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.
garments (clothes or linens) that are to be (or have been) ironed
“there was a basketful of ironing to do”
the work of using heat to smooth washed clothes in order to remove any wrinkles
Synonyms, antonyms and the broader and narrower relations for ironing come from Princeton University’s WordNet. Full sources and licences.