To set a dog or other animal on someone or something.
The farmer siced his dog on the intruders to chase them away.
To incite or urge to attack.
The coach siced his team on their opponents with a fiery pep talk.
sicadverb
Thus; used within brackets or parentheses after a quoted word or passage to indicate that it is reproduced exactly as in the source, including any errors.
The notice read "Keep off the grasss [sic]" with the extra 's' preserved.
Thus; in such a manner (archaic or literary, occasionally used outside of brackets).