403. a- or an.

The negation a- — an — is only used as the first member of compounds, both bahuvrîhis, and tatpurushas, see 218 and 223 c). In tatpurushas its force is not always the same. amitra f. i. not only denotes „not a friend” but also the very opposite of mitra, viz. „foe.” Of the latter kind are sundry common words, as analpa (much), aneka (many), ayaśaḥ (dishonour). The former type involves identity of meaning with the separate negation na, f. i. Daç. 69 aihikasya sukhasyābhājanaṃ jano ‘yam (I am no vessel for wordly pleasure), Panc. 62 teṣāṃ viyogaṃ draṣṭum aham asamarthaḥ = -na samarthaḥ, Daç. 199 kadācid apy avitṛṣṇo guṇeṣu (not a single moment [he was] not thirsting for virtue).

Further a- in tatpurushas may denote »all except this,” abrāhmaṇaḥ = »anybody but a brahman.” M. 5, 18 in the list of eatable animals it is said bhakṣyān… āhur anuṣṭrāṃś caikatodataḥ, Kull. comments tathoṣṭravarjitān ekadantapaṃkty upetān.

Rem. na is not wholly excluded from compounds, but it is rarely used so, f. i. nacireṇa = acireṇa (soon) etc.; nātidṛre (not far), napuṃsaka (eunuch; [the] neuter [gender]).

403. 否定辞a(n)-

否定辞a(n)-は、bahuvrīhiとtatpuruṣaの両方で、合成語の最初の要素としてのみ、用いられる。218と233-cをみよ。tatpuruṣaでは、その効力は常に同じである。amitraは例えば「非-友人」を表すのみでなく、mitraの正反対、すなわち「敵」をも表す。後者の類については、analpa（少なくない＝多くの＝much）、aneka（1つでない＝多くの＝many）、ayaśaḥ（不名誉）などのような種々の常用語がある。前者の類は、別の否定辞naと同じ意味を含む：
Daç. 69 aihikasya sukhasyābhājanaṃ jano ‘yam (I am no vessel for wordly pleasure)
Panc. 62 teṣāṃ viyogaṃ draṣṭum aham asamarthaḥ = -na samarthaḥ
Daç. 199 kadācid apy avitṛṣṇo guṇeṣu (not a single moment [he was] not thirsting for virtue)

加えて、tatpuruṣaのa-は「これ以外のすべて」（all except this）を表しうる；abrāhmaṇaḥ＝「バラモン以外の誰でも」。
M. 5, 18 in the list of eatable animals it is said bhakṣyān… āhur anuṣṭrāṃś caikatodataḥ
Kull. comments tathoṣṭravarjitān ekadantapaṃkty upetān

【補足】
naは完全に合成語から除外されるわけではなく、稀に合成語の一部として用いられる；nacireṇa＝acireṇa（すぐに）の他、nātidṛre（遠くない）、napuṃsaka（去勢された男；中性）など。