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Hrodna region of Belarus and south-eastern Lithuania has unusual mix ethnicities and cultures layering one on another in the last 1,000 years.
There is a surname Vajtukievič but not Vojtukievič in Belarus. Ukraine and Russia also have this surname which may suggest it’s Slavic origin. This surname is much more frequent in Belarus than both Ukraine and Russia combined despite Belarus is a small nation. Given that it is more common in Belarus from Hrodna and many Belarusians migrated in Russi and Ukraine then Baltic etymology cannot be ruled out.
On one Russian specialised website (UFOLOG) which I often consult I found two etymologies: http://www.ufolog.ru/names/order/Вайтукевич
1. Surname was formed from two words Vaja (Fern branch) and ‘Tuk’ (fat) . Such nickname could be given to an overweight person.
2. Surname is derived from word Vajkit (noise). In other word a noisy person. I don’t even know such word. I could not find it in dictionaries. Maybe in dialectical dictionaries? Dialects of north-western Belarus has around 1,200-1,300 Baltisms.
The first option is more plausible. But I don’t like either of them. It’s such an odd combination of fern branch (plant in forest) and fat to apply to an overweight person.
I like Lithuanian etymology better Vaitiukas/Vaitukas. Given that Hrodna region have autochthonous Balts living to this day I will not be surprised it is right one. We have man Belarusians who surnames with Lithuanian etymology .
PS The site above is Slavic oriented . Authors may not know Lithuanian etymology.