Manava Dharmashastra 1.63

1.63

atra sapta manavo mayā proktāḥ| anyatra caturdaśa paṭhyante | sve sve'ntare 'vasare prāpte'dhikārakāle iti yāvat | utpādya prajā āpuḥ pālitavantaḥ | svesve'ntare'dhikārāvasare, yasya manoryasminkāle prāptaḥ sargasthitipālanādhikāraḥ | anyè tvantaraśabdaṃ māsādiśabdavatkālaviśeṣavācinaṃ manyante | tadayuktam | manuśabdopasaṃhitaḥ kālaviśeṣaviṣayo 'manvantaro' nāma kālo, na tu kevala iti |

These seven almighty Manus, of whom Svāyambhuva is the first, having called into existence the whole of this world, consisting of movable and immovable beings, sustained it, each during his own regime.—(63)

Medhātithi’s commentary (manubhāṣya):
Here seven Manus have been mentioned by me; elsewhere they are spoken of as fourteen.

‘Each during his own regime’—during his time, i.e., during the time of his sovereignty.—‘Having called into being’ the offerings, they ‘maintained,’ nourished, them.—‘During his own regime’—means during the time of his sovereignty; i.e., that Manu whose time or turn it was to create and maintain the continuity of the world.

Others explain the term ‘antara’ as denoting a particular time-period, just like the words ‘month’ &c.

But this is not right; it is only when the term ‘antara’ occurs along with the term ‘Manu’ (i.e., in the compound ‘Manvantara’) that it becomes expressive of a time-period,—i.e., the time-period known ns ‘Manvantara,’—and not when it stands by itself (as it does in the text).