Tlustého

Tlustého is a grammatical form in Czech. It is the masculine animate genitive singular and the masculine animate accusative singular form of the adjective tlustý, which means fat or thick. In Czech, adjectives decline to agree with the nouns they modify, including by case and gender.

In practice, tlustého appears in phrases with masculine animate nouns. For example, in the sentence vidím tlustého muže, tlustého is the accusative singular form modifying muže (I see a fat man). In a phrase like barva tlustého psa, tlustého is the genitive singular form modifying pes (the color of the fat dog). Because masculine animate nouns use the genitive form in some contexts and the accusative form in others, tlustého can appear in both cases depending on the sentence’s syntactic role.

Beyond ordinary adjectives, tlustého also arises in the genitive form of the Czech surname Tlustý. In this use, tlustého marks possession or association with a person named Tlustý, as in a phrase referring to something belonging to or associated with that person.

Etymology traces tlustý to historical Slavic roots meaning thick or fat; the suffix -ý marks a typical masculine adjective ending in many Slavic languages, with tlustého being the inflected form for specific cases in Czech.

Summary: tlustého is not a standalone noun but a key inflected form of the adjective tlustý, used with masculine animate nouns in accusative and genitive cases, and also appearing as the genitive form of the surname Tlustý in proper-noun contexts.