köken: Probably from regional schwippen (“to sway, slant”) + Schwager (“brother-in-law”), thus “deviating, indirect brother-in-law”. For the verb compare Schwips (“tipsiness”). Alternatively a reduplicative ablaut derivation like Mischmasch, Schnickschnack, etc., but the -pp- is more readily explained by the first-mentioned theory.
brother-in-law (brother of one's spouse; husband of one's sibling)
çekim: çoğul langot · tamlayan langon
köken: From Proto-Finnic *lanko, borrowed from an unknown derivation of Proto-Germanic *langōną (whence Old English ġelangian, Old High German gilangōn). The original meaning was simply "relative", shifting into "relative by marriage, in-law" and finally "brother-in-law".
brother-in-law (the brother of one's spouse, husband of one's sibling or husband of one's spouse's sibling)
çekim: çoğul svogre · tamlayan svogers
köken: From Middle Low German swāger, from Proto-Germanic *swēgraz (“husband's brother”), cognate with German Schwager, Dutch zwager. Swedish svåger is also borrowed from Low German. The word goes back to Proto-Indo-European *swēḱurós (“husband's brother”), related to *swéḱuros (“father-in-law”) (German Schwäher, Latin socer) and *sweḱrúh₂ (“mother-in-law”) (German Schwieger, Latin socrus).