The meaning of Pali term 'tiracchānakathaṃ'


What is tiracchānakathaṃ?
Generally, Tirichanna means an animal.
Bhante @sujato But it was translated as “unworthy”
Why it was not translated as “animal talk”?

Now at that time, after the meal, on return from alms-round, several mendicants sat together in the meeting hall. They engaged in all kinds of unworthy talk, such as
Tena kho pana samayena sambahulā bhikkhū pacchābhattaṃ piṇḍapātapaṭikkantā upaṭṭhānasālāyaṃ sannisinnā sannipatitā anekavihitaṃ tiracchānakathaṃ anuyuttā viharanti, seyyathidaṃ—


Discussion from Dhamma Wheel.