Dëne Sųłıné (Chipewyan), an Athapaskan language of Northern Canada, has a clear distinction between count and mass nouns. The distinction is shown by semantic tests such as direct compatibility with a numeral. Crucially, however, count and mass noun phrases have identical morphosyntax—both are simply bare, numberless nouns. This challenges theories which assume that all bare nouns are in some sense mass, and that (singular) count denotations arise from "individuating" functional material such as number inflection or classifers (Greenberg 1990[1972], Longobardi 1994, Chierchia 1998a,b, Cheng and Sybesma 1999, Borer 2005, etc.). Instead, it will be argued that the Dëne Suliné pattern can only be explained if the count/mass distinction is lexicosemantic. Nouns (or roots) that denote "stuff" are inherently uncountable, while those that denote "individuals" are inherently countable. The lexicosemantic distinction is formalized using the model of Link (1983).