Natyashastra
यत्स्यादक्षरसम्बद्धं तत्सर्वं पदसञ्ज्ञितम् । निबद्धं चानिबद्धं च येन तेन द्विधा स्मृतम् ॥ २८॥
Whatever is connected with syllables (akṣara) is called Pada. It is remembered as being of two kinds: regularly composed (nibaddha) and not regularly composed (anibaddha).
english translation
yatsyAdakSarasambaddhaM tatsarvaM padasaJjJitam । nibaddhaM cAnibaddhaM ca yena tena dvidhA smRtam ॥ 28॥
hk transliteration by Sanscript