The term 'most irriguous' denotes a state of being excessively wet or waterlogged. Some antonyms for 'most irriguous' would include words such as dry, arid, parched, or barren. These words describe a lack of moisture or an environment that is too dry for flourishing plant growth. Other antonyms could include terms like desert, drought-ridden, or devoid, all painting a picture of a locale that is unable to sustain water or vegetation. Conversely, synonyms for 'most irriguous' could be something like marshy, damp, or wetland, describing an area where water is plentiful, and the ground is fully saturated.