The English name “June” comes from Latin iunius, the month of the Roman goddess Iuno (usually spelled “Juno” in English), who was the protector and special counsellor of the state. Words derived from the same root as “June” are shown on a red background in the map below:
Polish czerwiec, Ukrainian čérven’, Czech červen, Belarusian čérvjen’, and other similar variants, are related to the Slavic name of the colour red (*čьrvenъ in Proto-Slavic), likely referring to ripening apples, cherries, strawberries, and other fruits; the name of the colour itself is derived from *čьrvь (literally “worm”), which referred to a red insect used to make red dye, and some of the names may possibly be derived directly from *čьrvь. Croatian lipanj is the month of linden trees, which bloom in June. Lithuanian birželis is derived from beržas, “birch”.
Irish Meitheamh, Welsh Mehefin, Breton Mezheven, and Cornish Metheven are all derived from Proto-Celtic *medyo-samīno, which meant “mid-summer”. Scottish Gaelic Ògmhios is òg (“new”) + mìos (“moon”).
Finnish kesäkuu is derived from kesä (“summer”, archaically also “fallow”) + kuu (“month”), and the same is likely true for Karelian kezäkuu. Võro piimäkuu literally means “milk month”. North Sami geassemánnu means “summer month”.
Turkish haziran is borrowed from Aramaic via Arabic, from a word referring to wheat being cut down. Albanian qershor comes from qershi, “cherry” (which, in turn, comes from a Late Latin word for a cherry). Basque ekain is probably derived from eki (“sun”) + gain (“top, zenith”).
Finally, Sardinian is the only Romance language in the map which uses a word not derived from iunius. Làmpadas likely comes from Latin lampada, “lamp, lantern”.