Decode the Latin Motto You've Been Nodding Along To

It is carved above a doorway, printed on a crest, or tattooed on someone at a wedding, and you have been nodding along for years without knowing what it says. This gives you the literal translation, the actual meaning, and where phrases like it usually turn up. No more nodding.

Translate this Latin (or occasionally Greek or French) phrase into plain English: [phrase]. Give the literal word for word translation first, then the natural English meaning if the two differ. Note where the phrase commonly turns up, a family motto, a university crest, a pub sign, a scientific name, if that is obvious from the phrase itself, but do not invent a specific origin you cannot be confident of. Keep the whole answer under 80 words.