This is the 2394th most frequent Spanish word.
checo
"Checo" means "Czech" in English.
In this sentence, 'checo' refers to the Czech language.
El libro está escrito en checo.
The book is written in Czech.
In this sentence, 'checo' is used as an adjective to describe the nationality of a person.
Mi amigo es checo y vive en Praga.
My friend is Czech and lives in Prague.
Here, 'checo' refers again to the language as a subject of study.