Encephalous refers to having a large brain or being intellectually advanced. Its antonyms, on the other hand, describe a lack of intelligence or brainpower. Some antonyms for encephalous are feeble-minded, dull-witted, half-witted, and brainless. These words indicate a deficiency or absence of intellectual abilities, suggesting a low IQ or limited cognitive processing. Another set of antonyms may consist of terms that describe humans with smaller brain size, such as microcephalic. Other antonyms of encephalous, such as imbecile, moron, or idiot, are much more offensive and should not be used. In summary, encephalous is a positive term suggesting intelligence, and its antonyms are negative descriptors indicating low cognitive abilities.