deriv SD cv (967) ashtadhyayi.com hei.de L 967 ETT STT a 2.1.6 ALPH OLDHOMEPAGE NEWHOMEPAGE

avyayaM vibhakti; samIpa; samRddhi; vyRddhy-arthAbhAvAtyayAsamprati; zabda; prAdur- bhAva; pazcAd; yathA- ''nupUrvya; yaugapadya; sAdRzya; sampatti; sAkalyA; 'nta-vacaneSu

अव्ययं विभक्तिॱ समीपॱ समृद्धिॱ व्यृद्ध्यर्थाभावात्ययासम्प्रतिॱ शब्दॱ प्रादुर्भावॱ पश्चाद्यथाॱ ऽऽनुपूर्व्यॱ यौगपद्यॱ सादृश्यॱ सम्पत्तिॱ साकल्याॱ ऽन्तॱवचनेषु ONPANINI 21006

An indeclinable (/avyaya) employed with the sense of
a /vibhakti,
nearness,
prosperity,
adversity,
lack,
passed,
not now,
sound,
after,
according to rank,
simultaneity,
resemblance,
possession,
totality,
or termination,
(is compulsorily compounded with a word ending in a case-affix which is connected with it in sense).

And the compound so formed is called /avyayIbhAva.

These words are allowed only when they have special meanings. As for instance, upa kumbhasya उप कुम्भस्य ordinarily means "above the jar", and it cannot be replaced with upakumbham उपकुम्भम्. The /avyayIbhAva upakumbham उपकुम्भम् means kumnbhasya samIpe कुम्न्भस्य समीपे "near the jar", "what is near the jar", and is not allowed in other senses.