dishonorably has 6 distinct synonyms spread across 1 of its 3 senses. Each sense below keeps its own list, because a synonym belongs to a meaning and not to a word: swapping one sense's substitute into another sense's sentence is how a thesaurus makes writing worse. Its one recorded opposite is honorably.
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.
in a dishonorable manner
“he acted dishonorably”
with dishonor
“he was dishonorably discharged”
in a dishonorable manner or to a dishonorable degree
“his grades were disgracefully low”
Synonyms, antonyms and the broader and narrower relations for dishonorably come from Princeton University’s WordNet. Full sources and licences.