The word 'sic' can be used both as an adverb and as a verb and can seek its derivation in the Latin language. When you are using the word as an adverb you should write is after a word that you have copied from somewhere else. The idea behind the use of the word is that you want to show that the word is spelled in a wrong way or sometimes it is wrong in some other way. The following sentence can help you in understanding the word if you yourself want to use it: The following sentence is written in the school diary and it marks the irresponsibility of the teacher, 'Our school is proud of its (sic) excellent record. In the above mentioned sentence the person is conveying that though the school is proud of its record but still it makes such silly stakes.

When you are using the word as a verb you should add another 'c' with the word and the meaning it conveys is to attack somebody.