The word "handwavy" is used to describe an argument or explanation that is vague or lacking substance. Synonyms for handwavy include "vague", "flimsy", "incoherent", "weak", "unclear", and "inconclusive". Other similar words that can be used to describe a handwavy explanation include "specious", "superficial", "unconvincing", "ambiguous", "hazy", "imprecise", and "equivocal". Using any of these synonyms can help to convey the same meaning as handwavy, but may provide a more precise or nuanced understanding of the argument's deficiencies. When evaluating the validity of statements or explanations, looking for these types of words can help to identify when further clarification or evidence may be necessary.