Vedic Metre in its Historical Development c12.s3.4

c12.s3.4

166. In compounds of which the prior element is a noun (including adjectives, pronouns, and numerals), the final syllable of that element is long (i) if it is a case-form, as *akṣṇayādrúh*, *amājúr*, *tuávṛdha*; (ii) if it is a feminine stem in *-ā* or *-ī*, as *urvarā-jít*, *nadítama*, *senānī*; (iii) in most proper names, as *lópāmudrā*, *viśvámitra*; and occasionally (iv) in stems in *-u*, *ulúkhala*, *purū-táma*, and perhaps (v) in stems in *-an*, as *vṛṣāyúdh*. The prior element (vi) has always a long vowel before *-vṛdh* and perhaps in some other cases before *v*, and (vii) is occasionally found in some other words in positions favouring long quantity.