Natyashastra
नियताक्षरसम्बद्धं छन्दोयतिसमन्वितम् । निबद्धं तु पदं ज्ञेयं सतालपतनाक्षरम् ॥ ३१॥
That which is connected with a fixed number of syllables, furnished with metre and proper caesura (yati), and whose syllables fall in accordance with a time-measure (tāla), is to be known as a regularly composed (nibaddha) Pada.
english translation
niyatAkSarasambaddhaM chandoyatisamanvitam । nibaddhaM tu padaM jJeyaM satAlapatanAkSaram ॥ 31॥
hk transliteration by Sanscript