Left-handed for those that need clarification. :)
And even there, "left" is a pretty different concept from "left-handed".
On a different note, French for left is "gauche".
From American Heritage Dictionary 4th Ed. (En-En)
> sinister
> sin·is·ter (sĭnʹĭ-stər)
> adj.
> 4. On the left side; left.
> From Merriam-Webster's Collegiate 11 (En-En)
> sinister
> a. : of, relating to, or situated to the left or on the left side of something; especially : being or relating to the side of a heraldic shield at the left of the person bearing it
The bar sinister? Calling that a sense of the English word would commit you to saying that "vert" is English for "green", "gules" is English for "red", "or" is English for "gold", etc.