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.
Paretic strabismus is due to paralysis of one or several extraocular muscles. Nonparetic strabismus is not due to paralysis of extraocular muscles. Comitant (or concomitant) strabismus is a deviation that is the same magnitude regardless of gaze position.