mayyoudaoicibaDictYouDict[may 词源字典]
may: English has basically two words may, although one of them has now virtually split into two. The auxiliary verb may [OE] goes back ultimately to the Indo-European base *mogh-, *megh-, denoting ‘power, ability’, which also produced English machine, main, and might. Its Germanic descendant *magan lies behind German and Dutch mag, Swedish må, and Danish maa as well as English may.

The compound maybe dates from the 15th century, and dismay is also related. May the month-name [13] comes via Old French mai from Latin Maius. This was originally an adjective meaning ‘of Maia’, Maia being a Roman goddess and wife of Vulcan (her name may go back to the same source as Latin magnus ‘large’, and hence denote ‘growth’ or ‘increase’).

In the month of May the hawthorn comes into flower, and so in the 16th century the tree received the name may.
=> dismay, machine, main, might[may etymology, may origin, 英语词源]
may (v.1)youdaoicibaDictYouDict
Old English mæg "am able" (infinitive magan, past tense meahte, mihte), from Proto-Germanic root *mag-, infinitive *maganan (Old Frisian mei/muga/machte "have power, may;" Old Saxon mag/mugan/mahte; Middle Dutch mach/moghen/mohte; Dutch mag/mogen/mocht; Old High German mag/magan/mahta; German mag/mögen/mochte; Old Norse ma/mega/matte; Gothic mag/magan/mahte "to be able"), from PIE *magh- (1) "to be able, have power" (cognates: Greek mekhos, makhos "means, instrument," Old Church Slavonic mogo "to be able," mosti "power, force," Sanskrit mahan "great"). Also used in Old English as a "auxiliary of prediction."
MayyoudaoicibaDictYouDict
fifth month, early 12c., from Old French mai and directly from Latin Majus, Maius mensis "month of May," possibly from Maja, Maia, a Roman earth goddess (wife of Vulcan) whose name is of unknown origin; possibly from PIE *mag-ya "she who is great," fem. suffixed form of root *meg- "great" (cognate with Latin magnus). Replaced Old English þrimilce, month in which cows can be milked three times a day. May marriages have been considered unlucky at least since Ovid's day. May-apple attested from 1733, American English.
may (v.2)youdaoicibaDictYouDict
"to take part in May Day festivities," late 15c., from May. Related: Mayed; maying.