Other forms: happened, happens, happening
When something happens, it takes place. The accident happened at the crossroads just after six. Things happen to you as well, such as a puncture, a letter, a change of mind, and the first question anybody asks is what happened.
Happen also carries chance inside it. If you happen to be passing, come in. I happened to see her at the market. As it happens, I have the number right here. That use softens whatever follows, which is why English speakers reach for it constantly. The grammar needs care, because happen takes no object and never goes into the passive: the accident happened, never it was happened and never they happened an accident. For arranged events such as weddings and meetings, take place sounds better than happen.
1verbhappenTo take place; to occur.~92%
“Nothing much happens here between October and April.”
synonyms: occur, take place
2verbaffectTo affect somebody or something, by chance or by accident. Used with to.~3%
“Whatever happened to your hand?”
3verbverbTo do something by chance. Used with to and another verb.~3%
“I happened to be walking past when the alarm went off.”
4verbfindTo find something by chance. Used with on or upon.~2%
“They happened on a small church with the door standing open.”
Shares are an estimate: a language model read 31 sentences found in the wild and placed 31 of them on a sense — a count of our sample, not a measurement of English.
Also accepted in games: occur
Happen was built in Middle English on hap, the old word for chance or luck, with the ending -en that turns it into a verb, and Old Norse pushed it along the same way. The same hap sits inside happy, perhaps, haphazard and mishap, a family where everything turns on luck. So to happen is, at the root, to fall out by chance, which is why the word still carries a small shrug.
Middle English
happenen
English, today
happen
From Middle English happenen. From Middle English happenen, hapnen, augmented from Middle English happen (“to come to pass, happen”), perhaps from Old English hæppan (“to move accidentally, slip”) and/or from Old Norse happa, heppa, from Proto-Germanic hampijaną (“to fit in, be fitting”). Equivalent to hap + -en.
Etymology from Wiktionary, CC BY-SA