letní

Letní is a Czech adjective meaning "summer-related" or "of the summer season." It describes things connected with summer or occurring during the summer, such as letní počasí (summer weather), letní festival, letní dovolená, or letní oblečení. The form letní is used across genders and numbers (letní den, letní dny, letní dovolená) and is commonly combined with nouns to label events, activities, and conditions that take place in summer.

The word is derived from the noun léto, meaning summer, and ultimately from Proto-Slavic *lěto. It is cognate with similar Slavic terms such as Russian leto and Polish lato, which share the same root referring to the summer season. In Czech, the related adjective is letní, while the noun is léto; in other Slavic languages the corresponding forms vary but retain the same underlying meaning.

In addition to describing the season, letní is used in other contexts such as daylight saving time. In Czech, letní čas (summer time) denotes the period when clocks are moved forward for daylight saving, typically in the summer months, with the opposite being standardní or zimní čas (winter time). The term appears in everyday language, media, and official references when discussing summer activities, weather, or time adjustments.