To corroborate something is to make more certain of it with evidence. In a courtroom, witnesses might be called to corroborate a story put forth by a defendant. Early findings in scientific research might be corroborated by additional scholarly work or laboratory results. More broadly, corroborate means “to strengthen”—and since this term's debut in English in the first half of the 16th century, it has been used to refer to strengthening or reinforcing things materially, to strengthening the health of things or people, and to strengthening a claim or statement.
The noun brainchild is used to refer to a product of one’s creative work or thought (the child of one’s brain, of course!). This heady compound is used of events, campaigns, companies, or elaborate projects—or the animating idea behind them. Use of this term usually connotes a degree of admiration for something truly original, and is almost always used in the context of giving credit or attributing success to a certain creative individual. So where there is a brainchild, there is usually a "brain parent" mentioned nearby.
Something that is incessant continues without interruption—and is more often than not a source of irritation! Incessant chatter near your workstation might disrupt your concentration; incessant whining in any circumstance might deplete your patience; and incessant demands, as from a boss or from any other source, might make you feel exhausted or taken for granted (or both!). When not used to describe undesirable situations such as these, you may find incessant used in a more neutral sense to describe continuous and unrelenting rainfall, or other weather events that carry on seemingly to no end.