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 (from Greek, cross or x): A literary scheme in which the author introduces words or concepts in a particular order, then later repeats those terms or similar ones in reversed or backwards order. It involves taking parallelism and deliberately turning it inside out, creating a crisscross pattern.