Emily Dickinson Lexicon

SIN'IS-TER, a. [L. Probably the primary sense is weak, defective.]

1. Left; on the left hand, or the side of the left hand; opposed to dexter or right; as, the sinister cheek; or the sinister side of an escutcheon.
2. Evil; bad; corrupt; perverse; dishonest; as, sinister means; sinister purpose. He scorns to undermine another's interest by any sinister or inferior arts. – South.
3. Unlucky; inauspicious. – B. Jonson. Sinister aspect, in astrology, an appearance of two planets happening according to the succession of the signs; as Saturn in Aries, and Mars in the same degree of Gemini. Encyc.