Code coverage means, how well your test set is covering your source code. i.e. to what extent is the source code covered by the set of Test cases. As mentioned in above answers, there are various coverage criteria, like paths, conditions, functions, statements, etc.
Chiasmus. Definition: Chiasmus is a specific type of parallelism. It consists of two parallel phrases in which corresponding words or phrases are placed in the opposite order.
Definition of Chiasmus. Chiasmus employs two or more clauses which are related grammatically and conceptually, but in which the grammar and concepts are reversed. Chiasmus is a figure of speech that displays inverted parallelism. A simple chiasmus can be broken into parts labeled ABBA.