Rūsteika

Cf. Rustei̇̃kis, Rūstỹs (see). It is not entirely clear whether the vowel ū in the root of these surnames is genetically long or later lengthened (due to the influence of the word rūstùs or similar). If the root rust- was from rust-, then see about it. Rustic. And the root rust- could be derived from lit. wrath „piktas, žiaurus; šiurkštus, užgaulus; atšiaurus; rūškanas, nemalonus; griežtas; niūrus, suniuręs; liūdnas“ (LKŽ XI 1027).