поўнасцю

• по́ўнасьцю (póŭnasʹcju) — Taraškievica orthography
• poŭnaściu — Łacinka (Belarusian Latin alphabet)

по́ўны (póŭny, “full”) +‎ -асць (-ascʹ) as *по́ўнасць (*póŭnascʹ, “fullness”), further inflected in the instrumental case (literally, “with fullness”), although the original noun is now obsolete. Compare Russian по́лностью (pólnostʹju), Ukrainian по́вністю (póvnistju).

• IPA^(key): [ˈpou̯nasʲt͡sʲu]

по́ўнасцю • (póŭnascju)

1. fully, in full
2. completely, entirely, wholly

   Synonyms: зусі́м (zusím), ца́лкам (cálkam)

• “поўнасцю” in Belarusian–Russian dictionaries and Belarusian dictionaries at slounik.org
• “поўнасцю”, in Skarnik's Belarusian dictionary (in Belarusian), based on Kandrat Krapiva's Explanatory Dictionary of the Belarusian Language (1977-1984)