The noun pinnacle is used to talk about the highest or culminating point of something, most commonly the time in one’s career when they are most successful or a specific achievement that caps one's career. In architecture, a pinnacle is a small, upright structure rising above the roof of a building or capping a tower. In nature, a pinnacle is a lofty peak of a mountain or a pointed, towering part of a rock formation. The theme of capping, crowning, or being positioned atop something is what threads these senses together. The more general word peak is the appropriate choice for talking about maximum prices (oil prices reached their peak) or maximum volume (traffic was at its peak).

To illuminate is to supply with light or to light up. But this verb is not used in exactly the same way as the much more general verb light. For instance, light is more appropriate to talk about the action of igniting or setting something to burn, as a candle. But illuminate is more appropriate for talking about what that lit candle will do: illuminate the room! Stars illuminate the night sky, just as festive lights illuminate residential streets during the holidays. To illuminate a path forward is to shed light on the best course of action—unless of course the path is a literal one from, say, the mailbox to the front door after sunset. In which case, a flashlight should do the trick! Illuminate can also refer to shedding light on a subject, as if to make it more clear or comprehensible.

To fret over something is to feel or express worry, annoyance, or annoyance about it. The earliest senses of this term in English had to do with devouring or consuming in the literal sense—as in moths fretting your favorite sweater (heaven forbid!). The verb has of course evolved since then, with the theme of consuming taking a turn: rather than expressing the act of consuming, fret now conveys being consumed or eaten by something. Interestingly, the critters who would do the fretting were usually small (like moths), which perhaps explains why the current sense of fret suggests incremental or gradual gnawing away at one’s peace of mind.

Something that is typical is characteristic or distinctive of a certain type or specimen. Something that is quintessential is not only characteristic or distinctive of a type, but goes a step further to capture the pure and essential essence of it—or to embody it perfectly. Quintessential is used to talk about people or things that are exactly as one might imagine or hope for them to be, based on widely circulated and understood ideas or ideals.

To safeguard something is to guard, protect, or secure it. Often this term suggests taking forceful measures to ensure something does or does not happen. As a result, the term conveys a degree of assurance that the safety of something is guaranteed. Safeguard is more likely to be used of ideas or concepts—immaterial things—than it is of property or physical objects. For instance, you’re more likely to hear of a leader or governing body taking measures to safeguard the rights of a specific group than to safeguard a wetland, the latter being better suited for use with the verb protect.

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.