Agog: The word probably derives from the Middle French phrase en gogues, but the semantic link between en gogues (meaning "in a state of mirth") and the earliest English uses of agog, which exist in the phrase "to set agog" ("to excite, stimulate, make eager"), are not entirely clear. The -gog part of the word might make one wonder if agog has a connection to the verb goggle, meaning "to stare with wide or protuberant eyes," as in the manner of one who is intensely excited about something. That word actually has a different origin: the Middle English gogelen, meaning "to squint." In many instances, agog is followed by a preposition, such as over or about.
In the early era of firearms, cannons of lesser size such as the falconet were sometimes named for birds of prey. Following this pattern, Italians applied moschetto or moschetta, meaning "sparrow hawk," to a small-caliber piece of ordnance in the 16th century. Spaniards borrowed this word as mosquete, and the French as mosquet, but both applied it to a heavy shoulder firearm rather than a cannon; English musket was borrowed soon thereafter from French. The word musket was retained after the original matchlock firing mechanism was replaced by a wheel lock, and retained still after the wheel lock was replaced by the flintlock. As the practice of rifling firearms—incising the barrel with spiral grooves to improve the bullet's accuracy—became more common, the term musket gradually gave way to the newer word rifle in the 18th century.
Gloss as a noun meaning "shine," or as part of the phrase gloss over, meaning "to treat or describe (something) as if it were not important," but those uses are unrelated to the modern meaning of gloss.
Gloss comes from the noun gloss that refers primarily to a brief explanation. It is Greek in origin, coming from glossa or glotta, meaning "tongue," "language," or "obscure word."
Glossary is from this same root, as are two anatomical terms: glottis refers to the elongated space between the vocal cords and also to the structures that surround this space; epiglottis refers to the thin plate of flexible cartilage in front of the glottis that folds back over and protects the glottis during swallowing.
In medieval Europe, a bell rang every evening at a fixed hour, and townspeople were required by law to cover or extinguish their hearth fires. It was the "cover fire" bell, or, as it was referred to in Anglo-French, coverfeu (from the French verb meaning "to cover," and the word for "fire").
By the time the English version, curfew, appeared, the authorities no longer regulated hearth fires, but an evening bell continued to be rung for various purposes—whether to signal the close of day, an evening burial, or enforcement of some other evening regulation.
This "bell ringing at evening" became the first English sense of curfew. Not infrequently, the regulation signaled by the curfew involved regulating people's movement in the streets, and this led to the modern senses of the word.