The word "Polish" has two common, distinct senses. With a capital P it identifies things connected to the Central European country of Poland, its people and institutions. With a lower-case p, "polish" names a physical process, a cosmetic or finishing substance, or a figurative improvement in style or quality.
As an adjective, demonym and language
Capitalized Polish is used for national, cultural and linguistic references. It describes the Poles as a people, customs, cuisine and other cultural forms. It also denotes the Polish language, a West Slavic language written in a Latin alphabet with characteristic diacritics (for example: ą, ć, ę, ł, ń, ó, ś, ź, ż). The term appears in compound names (Polish literature, Polish law, Polish cuisine) and in identifiers for institutions and products tied to Poland.
- Geographic/civic use: relating to the state, its regions and institutions.
- Ethnic/cultural use: traditions, arts, and shared heritage of Poles.
- Linguistic use: the language of Poland and its dialects.
As a verb and noun (polish)
Lower-case polish is unrelated etymologically to Poland. It comes from Old French and Latin roots meaning "to make smooth." As a verb, to polish means to buff or refine a surface so it shines or to improve something's appearance or performance. As a noun, polish refers to a substance applied to create sheen (shoe polish, metal polish, nail polish) or to the smooth finish itself. In everyday speech it also denotes refinement of style or technique: a presentation may need "some polish."
Both senses are widely encountered and usually clear from context. Capitalization signals whether the reference is national/cultural or practical/technical: Polish versus polish. For further reading on the country, language or people, see links above.