A case-inflected word denoting a genus (jāti) is compounded with the words poṭā 'a hermaphrodite', yuvati 'a young female', stoka 'a little', katipaya 'a few', gṛṣṭi 'a cow which has had only one calf', dhenu 'milch cow', vaśā 'a barren female', vehad 'a cow that miscarries', baṣkayaṇī 'a cow that has a full-grown calf', pravaktṛ 'an expounder', śrotriya 'a learned brāhmaṇa ', adhyāpaka 'a teacher' and dhūrta 'a cunning fellow' and the resulting compound is tat-puruṣa ,
As इभपोटा 'a young female elephant' इभयुवति 'a female elephant.' So also अग्निस्तोकः 'a little fire' उदश्वित् कतिपयम् 'a little butter milk,' गोगृष्टिः , गोधेनुः, गोवशाः , गोवेहत् , गोवष्कयणी, कठप्रवक्ता 'an expounder of Katha', कठश्रोत्रिय, 'a Bráhmana who has mastered the Katha branch of the Yajur Veda' कठाध्यापकः 'a teacher of the Katha branch of the Yajur Veda.'
Why do we say 'when denoting a genus or a common noun ?' Observe देवदत्तः प्रवक्ता 'Devadatta expounder.'
The word धूर्त has not a bad signification here. Hence कटधूर्त means 'a Brahmana well versed in the Katha branch of the Yajur Veda.',