The English language hasn't been kind to left-handed people. Sinister used to mean left. So did gauche, and cack-handed.
Sinister came from the Latin word sinus, which means pocket. (A toga had its pocket on the left side.) My Latin teacher told me once that if a Roman used his left hand his toga fell off, and perhaps this is why sinister began to have its current threatening meaning.
Gauche is a French word which means awkward (though it still means left, too). It's from the Old French gauchir to swerve.
Cack-handed means clumsy, as well as left-handed, and probably has an even less complimentary origin than the others.
On the other hand (sorry!) an Inca left-hander can do magic and heal people; in some sorts of Buddhism left-handers are known for their wisdom; in Japan the left hand is the hand of work; and in Russia levsha, a lefty, means a skilled craftsman.
And of course if you're writing Arabic, Persian, Urdu or Hebrew, which run right to left, then being a left-hander might even be an advantage.
There's some research to suggest that clever left-handers earn more, too.
I'm beginning to feel quite left-out!*
Word To Use Today: sinister is a great word, and luckily, like gauche, it's now lost its shades of left-handedness.
*Do feel free to groan.