Inherited from Old Ruthenian отмовитисѧ (otmovitisja). By surface analysis, адмо́віць (admóvicʹ) +‎ -ца (-ca). Compare Ukrainian відмо́витися (vidmóvytysja).

• IPA^(key):
• Rhymes: -ovʲit͡sːa
• Hyphenation: ад‧мо‧ві‧цца, ад‧мо‧віц‧ца

адмо́віцца • (admóvicca) pf (imperfective адмаўля́цца)

1. to refuse (to express one's disagreement with doing something)
2. to reject

   Synonym: адхілі́ць (adxilícʹ)

3. to abandon, to disown (to break ties with relatives, loved ones)

   Synonym: адрачы́ся (adračýsja)

4. to renounce (to not recognize as one's own, not to confirm something)
5. to renege on, to renounce (to cease to hold on to something, to retreat from something)
   • 2025, Гіпаліт Корвін-Мілеўскі, Успаміны пра семдзесят гадоў (1855–1925)‎, ЛитРес, →ISBN:

     А панí Клемянцíна разумéла спрáву зусíм па-íншаму, яна не сумнявáлася ў тым, што я не адмóўлюся ад ранéйшага абяцáння і не паéду да яе, каб тóлькі яго пацвердзíць.

     A paní Kljemjancína razuméla správu zusím pa-ínšamu, jana nje sumnjaválasja ŭ tym, što ja nje admóŭljusja ad ranéjšaha abjacánnja i nje paédu da jaje, kab tólʹki jahó pacvjerdzícʹ.

     But Mrs. Klementina understood the matter completely differently; she had no doubt that I would not renege on my previous promise and would not go to her just to confirm it.

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