The word "flashest" is not a recognized word in the English language. However, if we were to consider antonyms for the term "flash", we could look at words like "dull", "dim", or "gloomy". These words all suggest a lack of brightness or intensity, and in the context of "flashing", they may indicate a lack of energy or excitement. Other antonyms for "flash" might include words like "fade", "subside", or "dwindle", which all suggest a reduction in strength or intensity. Ultimately, the exact antonyms for "flashest" will depend on the intended meaning behind the term, and the context in which it is used.