The process by which something is retrofitted.

(sports) A heat (as in rowing or fencing) in which the best competitors who have lost in a previous round compete for a place or places yet left in the next round.

(of a sound or sound waves, intransitive) To reflect off a surface and return. / (transitive) To reflect back (a sound). / (by extension, transitive) To repeat (another's speech, opinion, etc.).

simple past tense and past participle of view