slyšel na hrozné jméno Antoušek

Gramatika: slyšet na A(něco) - to answer or react (e.g. to a name). This expression is often used for pets. Instead of using the standard jmenovat se, Čapek is presenting the giant's name this way so Dáša would understand it better. antoušek with a small a is a dog catcher/animal control person (pohodný, ras). The term is based on a dog catcher's name (Anton Scheck). Čapek is using this name for the terrible giant because it would sound scary to Dášeňka.