Parsing inflected forms may not always work as expected. If the following does not give the correct word, try Latin Words or Perseus.
carbōnārĭus, a, um, adj. [1. carbo], 
- I. of or relating to charcoal: negotium, traffic in charcoal, Aur. Vict. Vir. Ill. 72.
 
- II.  Subst. 
 
- A.  carbōnārĭus, i, m., a burner of charcoal, a collier, Plaut. Cas. 2, 8, 2; Inscr. Orell. 4302.
 
- B.  carbōnārĭa, ae, f. 
 
- 1.  (Sc. fornax.) A furnace for charcoal, Tert. Car. Christ. 6.
 
- 2.  (Sc. femina.) The Charcoal-Woman, the title of a lost play by Plautus, Fest. p. 30, 27 Müll.