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.
There are several types: infantile strabismus, acquired non-accommodative strabismus, basic esotropia (no significant hyperopia and the deviation is equal for near and distance), microtropia, convergence excess (esotropia for near vision but not for distance), divergence insufficiency (esotropia for distance vision but not for near), consecutive strabismus, sensory strabismus and cyclic esotropia (periodic manifestation of esotropia as for example on alternate days).