From WordNet (r) 2.0 (August 2003) [wn]:
happen
v 1: come to pass; "What is happening?"; "The meeting took place
off without an incidence"; "Nothing occurred that seemed
important" [syn: hap, go on, pass off, occur,
pass, fall out, come about, take place]
2: happen, occur, or be the case in the course of events or by
chance; "It happens that today is my birthday"; "These
things befell" (Santayana) [syn: befall, bechance]
3: chance to be or do something, without intention or
causation; "I happen to have just what you need!"
4: come into being; become reality; "Her dream really
materialized" [syn: materialize, materialise] [ant:
dematerialize]
5: come upon, as if by accident; meet with; "We find this idea
in Plato"; "I happened upon the most wonderful bakery not
very far from here"; "She chanced upon an interesting book
in the bookstore the other day" [syn: find, chance,
bump, encounter]
From The Collaborative International Dictionary of English v.0.48 [gcide]:
Happen \Hap"pen\ (h[a^]p"p'n), v. i. [imp. & p. p. Happened
(-p'nd); p. pr. & vb. n. Happening.] [OE. happenen, hapnen.
See Hap to happen.]
1. To come by chance; to come without previous expectation;
to fall out.
[1913 Webster]
There shall no evil happen to the just. --Prov. xii.
21.
[1913 Webster]
2. To take place; to occur.
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All these things which had happened. --Luke xxiv.
14.
[1913 Webster]
To happen on, to meet with; to fall or light upon. "I have
happened on some other accounts." --Graunt.
To happen in, to make a casual call. [Colloq.]
[1913 Webster]