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.
Chiasmus Definition. Chiasmus is a rhetorical device in which two or more clauses are balanced against each other by the reversal of their structures in order to produce an artistic effect. Notice that the second half of the above mentioned sentence is an inverted form of the first half both grammatically and logically.