The verb happen has 5 senses (first 4 from tagged texts)
1. (150) happen, hap, go on, pass off, occur, pass, fall out, come about, take place -- (come to pass; "What is happening?"; "The meeting took place off without an incidence"; "Nothing occurred that seemed important")
2. (20) happen, befall, bechance -- (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))
3. (17) happen -- (chance to be or do something, without intention or causation; "I happen to have just what you need!")
4. (9) happen, materialize, materialise -- (come into being; become reality; "Her dream really materialized")
5. find, happen, chance, bump, encounter -- (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")