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.

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.

Something that is stale has lost freshness, such as a stale slice of bread, or has lost novelty or interest, such as a stale joke. That crusty old joke may also be described as hackneyed. Something that is hackneyed is commonplace or trite and worn out by overuse. This term is especially used of words, remarks, or styles of expression that are clichéd to the point of seeming lifeless and uninteresting. So synonym seekers beware: while it may be tempting to slather this adjective on a piece of stale bread, hackneyed simply doesn't make sense as a descriptor for brittle day-old baked goods!

To allay something is to put it to rest or to quiet it. This sense of the word is mostly used to talk about laying to rest fear, doubt, suspicion, or anger, possibly by making the emotion seem unjustified. Allay is also used to talk about lessening or mitigating something, such as pain. Soothe is similar (an ointment can soothe sunburned skin, for instance). But a key difference is that soothe is sometimes used to talk about people (rather than their concerns or fears)—and in these cases, it may suggest tranquility and even comfort. A person might be soothed or comforted by a warm cup of tea, for instance, but not allayed.