letními

Letnými is a Slovak grammatical form, specifically the instrumental plural of the adjective letný, which means "summer" or "pertaining to summer." It is used to modify masculine or mixed nouns in the instrumental case and appears in phrases describing time, manner, or conditions associated with summer.

Morphology and usage: In Slovak, adjectives change form to agree with the noun they modify in gender, number, and case. The instrumental plural letnými is used after prepositions that require the instrumental case or in adverbial expressions. This form is distinct from the Czech equivalent letními, which serves the same grammatical purpose in Czech but uses a slightly different orthography.

Examples of use:

- s letnými dňami (with the summer days / during the summer days)

- letnými večermi (by summer evenings / during summer evenings)

- letnými aktivitami (with summer activities)

Relation to related terms: The root letný/letné (Czech: letní; Slovak: letný) derives from the word for summer (léto in many Slavic languages). The form letnými is part of a broader inflection pattern shared by Slavic adjectives describing seasonal or temporal qualities. A closely related term in Slovak is letný in other cases, while in Czech the corresponding instrumental plural form is letními. The proper noun Letná (a district in Prague) is unrelated to the grammatical form, despite phonetic similarity.

See also: letný, letné, letný výraz, Letná (geographical name)

Note: This article focuses on the grammatical usage of the form letnými in Slovak and its Czech cognate in the instrumental plural.