The term "pindownable" refers to something that is difficult to define, explain, or identify clearly. Antonyms for this word would include terms like clear, definable, specific, certain, precise, and determined. These words all suggest that something can be easily understood, accurately described, or without doubt or uncertainty. Conversely, other antonyms for "pindownable" might include vague, ambiguous, obscure, uncertain, and hazy. These words suggest that the subject at hand is not well-defined or is open to interpretation, making it difficult to pinpoint or identify with accuracy. Overall, the antonyms for "pindownable" all suggest clarity or lack thereof, depending on the specific term used.