Definition of sinistrorsal in English:

sinistrorsal

Pronunciation /ˌsɪnɪˈstrɔːsl/

adjective

rare Zoology
  • Designating spiral mollusc shells that coil to the left (anticlockwise), and molluscs having such shells.

Origin

Early 19th century (in an earlier sense). From post-classical Latin sinistrorsus sinistrorse + -al.