The indeclinable word ku 'bad' , the particles called gati and the prepositions pra etc. are invariably compounded with other words with which they are in construction and the resulting compound is tat-puruṣa,
The word ku means 'badness or sin' ; as, कुपुरुषः 'a sinful man' ; (2) Gati 1.4.60 as, उररीकृतं 'having asserted'; (I. 4. 61.) यदूरीकरोति ॥
So also with the words प्र &c., when they are mere particles and not used as 'upasargas,' or 'gati'; as दूर् meaning 'bad,' in दुष्पुरुषः 'a bad man'; so also सु and अति meaning 'respect' in सुपुरुषः 'honorable man'; अतिपुरुषः 'excellent man' ; आ means 'a little' as आपिङ्कत्नः 'brownish.'
Generally these are attributive words but they are found elsewhere also, as कोष्यं or कदुष्णम् or कवोष्णन् 'tepid.' So also दुष्कृतम्, अतिस्तुतम् and आबद्धम् ॥,