This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

adj. which suffers so many constraints that it has no solution.

adj. which has more equations than variables.

adj. be determined by multiple causes in such a way that any of the causes on its own would be sufficient to account for the effect.

"Also, for what it is worth, the word overdetermined always has connotations of Althusser for me."

underdetermined