"Redblooded" is an adjective that is often used to describe someone who is robust, hearty, and full of life. It implies physical strength, vitality, and courage. Its opposite antonyms might include adjectives such as weak, frail, anemic, or timid. These words would suggest a lack of energy or courage, or possibly a deficiency in physical or emotional health. Some other antonyms might include words like lethargic, feeble, spineless, or pusillanimous. These terms would suggest a weakness or lack of conviction, in addition to the lack of vitality that is implied by the word "redblooded." Regardless of the context, antonyms for "redblooded" emphasize the opposite qualities with which this adjective is typically associated.