köken: From Middle High German sumer, from Old High German sumar, from Proto-West Germanic *sumar. The expected modern form is Summer, as indeed found in most southern dialects, such as Alemannic German Summer, Bavarian Summer and Luxembourgish Summer. The vocalism -o- is of Central and Low German origin (compare Middle Low German som[m]er). Further cognates are Dutch zomer, West Frisian simmer, English…
summer, summertime (season, time of year) · summer time, daylight saving time (part of the year when clocks are advanced one hour ahead of standard time)
köken: From Proto-Finnic *kesä (compare Estonian kesa (“fallow”), Veps keza (“summer”), Võro kesä (“fallow”)), from Proto-Finno-Permic *kesä (“summer”) (compare Northern Sami geassi, Erzya кизэ (kizë)), possibly a loanword from Indo-European; see it for more. Introduced from the eastern dialects into the standard language in the 19th century to replace the Western Finnish word suvi.
köken: From Old Galician-Portuguese verão (13th century, Cantigas de Santa Maria), from Vulgar Latin (tempus) *veranum, from Latin vēr (“spring”). Cognate with Portuguese verão and Spanish verano.