May is the quiet way of saying perhaps. It may rain, she may already know, there may be a delay. It hedges: everything after may is possible rather than settled, which is why letters and notices are full of it.
It is also the polite way to ask and to allow — may I come in, you may sit down — where it is a shade more formal than can. And it is the fifth month, which is the only use of the word that is a thing rather than a shade of meaning. Careful with may and might: they overlap so much that most speakers use them interchangeably, and nobody minds.
1verbmodalUsed to say something is possible, or to ask for and give permission.~98%
“It may rain later, so may I borrow your umbrella?”
2nounmayThe fifth month, when flowers are everywhere.~2%
“The garden is at its best in May.”
Shares are an estimate: a language model read 15 sentences found in the wild and placed 15 of them on a sense — a count of our sample, not a measurement of English.
May and might come from Proto-Germanic maganą, to be able, and behind that the root megh, to be able. The permission sense grew out of capability: you may first meant that you could, not that you were allowed.
Proto-Indo-European
*megʰ-
Proto-Indo-European
*(me)mógʰe — to be able
Proto-Germanic
*maganą — to be able, may
Proto-West Germanic
*magan
Old English
magan
Middle English
magen
English, today
may
Built from
From Middle English magen, mauen, mawe, mawen, mayen, maȝen, mouin, mow, mowen, moȝen, mugen, from Old English magan, from Proto-West Germanic magan, from Proto-Germanic maganą (“to be able, may”), from Proto-Indo-European (me)mógʰe (“to be able”), from megʰ- (“to be able”). 2 Cognate with Scots mey (“may”), yol ma, maa, mai, mey, mye (“may”), frr mai, mei, mooge (“like to, would”), West Frisian meie (“may; to like”), gsw möge (“may; can”), bar megn (“to like; to want to”), gmw-cfr mugge (“to like; may”), cim mögan, möng (“may”), Dutch mogen (“to be allowed; may; to like”), German and Low German mögen (“to like; would like; may”), Yiddish מעגן (“may”), Danish måtte (“have to; may”), Faroese and Icelandic mega (“may; must”), Norwegian Bokmål måtta (“may; must”), Norwegian Nynorsk måtta, måtte (“may; must”), Swedish må (“may; must”), Gothic 𐌼𐌰𐌲𐌰𐌽 (“to be able, can, may”); also Irish smacht (“ordinance, regulation, rule; dominion, sway; control, discipline, restraint; fine, penalty”), Lithuanian mėgti (“to like”), be магчы́ (“to be able”), Bulgarian мо́га (“to be able”), Czech moci (“to be able”), csb mòc (“to be able”), dsb moc, móc, moz (“to be able”), mk може (“to be able”), rsk мочи (“to be able”), Polish móc (“to be able”), Russian мочь (“to be able”), Serbo-Croatian мо̏ћи, mȍći (“to be able”), Slovak môcť (“to be able; be allowed to”), Slovene moči (“to be able”), zlw-slv môc (“to be able”), Ukrainian могти́ (“to be able”), Persian مغ (“magus”), Sanskrit मघ (“power, wealth; bounty, gift, reward”).
Etymology from Wiktionary, CC BY-SA