WordNet records no synonym and no antonym for trowel. 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 small hand tool with a handle and flat metal blade; used for scooping or spreading plaster or similar materials
Synonyms, antonyms and the broader and narrower relations for trowel come from Princeton University’s WordNet. Full sources and licences.
use a trowel on; for light garden work or plaster work