sin·is·tral 
(sĭnĭ-strəl, sĭ-nĭstrəl)
(sĭnĭ-strəl, sĭ-nĭstrəl)adj.
1. Of or facing the left side.
2. Left-handed.
3. Zoology Relating to or being a gastropod shell that has its aperture to the left when facing the observer with the apex upward.
sinis·tral·ly adv.