The term "neurologic mercurialism" refers to a condition caused by mercury poisoning, which can result in symptoms such as tremors, memory loss, and mood swings. Antonyms for this term would be words that describe opposite concepts or states of being. For example, instead of being "neurologic," someone might be "neurologically healthy" or "neurologically normal." Similarly, instead of "mercurial," they might be "steady," "consistent," or "stable." Other possible antonyms for this term could include "balanced," "calm," "clear-headed," "grounded," "mellow," "peaceful," "rational," "serene," "sober," and "unwavering.