Sinciput: in Coleoptera; that part of the vertex between the eyes.
Sinistrad: toward the left.
Sinistral: extending to or at the left from the median line.
Sinistro-caudad: extending obliquely from the left toward the tail.
Sinistro-cephalad: extending obliquely from the left toward the head.
Sinuate: cut into sinuses; applied to lines and margins with an in and out curve.
Sinuated: winding: with the edge scooped into sinuses.
Sinuato-convex: sinuate and convex.
Sinuato-lobate: sinuate and lobed.
Sinuato-truncate: truncated, with the margin sinuate.