sinistromanual UK /ˈsɪ.nɪs.tɹəʊˌman.jʊ.əl/US /ˈsɪ.nɪs.tɹoʊˌmæn.jə.wəl/adjective 1noun 1forms 1 adjective1 •Left-handed."Precisely. Whoever killed this young girl was sinistromanual, an unusual state in this day." / "My murderer was left-handed? That is most unusual, I agree. How do you come to that finding?" — 2012 noun1 •(rare) A person who is left-handed. formssinistromanuals