murderess / murderous are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
murderess: (noun) a woman murderer.
murderous: NA
murderess: NA
murderous: m·ER·d·er·ah·s
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)