"Medicaster" is a rare word that implies someone who pretends to possess medical knowledge or expertise without having actual qualifications. Synonyms for this term would include "quack," "impostor," "charlatan," "fraud," "mountebank," "sham," "poser," "pretender," and "pseudo-doctor." All of these words convey a sense of deception and dishonesty, suggesting that the person in question is trying to mislead others into thinking they have medical skills or knowledge. It's important to be cautious of individuals claiming to be medical experts who lack proper qualifications, as their advice or treatment could potentially be dangerous.