Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
1. exstinctus (ext-), a, um, Part., from exstinguo.
* 2. exstinctus (ext-), ūs, m. [exstinguo], an extinguishing: lucernarum exstinctu, Plin. 7, 7, 5, § 43.
extinctus, extinguo, etc., v. exstinctus, exstinguo, etc.