You can’t go wrong with the adjective stormy (stormy seas or a dark and stormy night) for describing things affected or characterized by a storm. Tempestuous is a valid synonym for stormy in this literal context (tempestuous ocean), as long as you’re aware that tempest is an old-fashioned, non-meteorological, literary word for “storm.” Tempestuous is more frequently used in its figurative sense of “turbulent or tumultuous,” and is a strong synonym for stormy’s figurative sense. Tempestuous is often used to describe relationships, as in a tempestuous marriage, full of passion and door-slamming. A difficult, unpredictable person prone to outbursts may themselves have a tempestuous personality. The word is also regularly called on to characterize social, political, and economic climates (the tempestuous years before the war).

Worsen and exacerbate both mean to make something bad worse, and they can be used interchangeably in many contexts. A physician might tell you that fatigue will worsen your symptoms, while a medical textbook would say that fatigue exacerbates the symptoms of a disease. Worsen is a grammatically looser verb, in that, unlike exacerbate, it can be used without an object: the weather worsened. However, it’s also a blunt instrument compared with exacerbate, whose exactness gives it a sharper edge. Exacerbate means specifically to increase the severity, bitterness, or violence of something that’s already a problem (exacerbate tensions). It comes from a Latin word meaning “harsh” or “bitter” in taste, which may be why, in contrast to the more gradual progression of worsening, the word exacerbate suggests a more immediate and intense effect.

The noun piece can mean a portion, part, or unit of something and has numerous definitions, giving it a broad range of application: a piece of cake, a piece of land, a piece of furniture, a piece of music, a piece of pottery. One of its definitions overlaps with the core meaning of the synonym fragment: a part that is broken off or detached (scattered fragments of the broken vase). By itself, piece is more general and ambiguous: a piece of pottery is more likely to mean an individual bowl or mug than a broken-off piece, whereas there’s no mistaking what a fragment of pottery refers to. While piece and fragment both name things that are less than whole, the connotations of fragment are more particular: fragment suggests a broken, inconsequential, incomplete part, with irregular or imprecise outlines or boundaries.