happen-v; 3 Senses

Sense Number 1: occur, materialize or come about

Commentary: Syntax Includes: NP1 HAPPEN[intransitive] PP{P NP[topic]}

This is what's been happening in the energy spot markets.
Who knows what will happen in the Middle East.
Stuff happens.
Whatever happened to poodle skirts and saddle shoes?
His biography is full of events that may not have really happened.

VerbNet: occurrence-48.3.1
FrameNet: Event
PropBank: happen.01
WordNet 3.0 Sense Numbers: 1, 2, 4

Sense Number 2: by chance, coincidentally

Commentary: Syntax Includes: NP1/Pro(IT) HAPPEN THAT SCOMP[finite] NP1/Pro(IT) HAPPEN SCOMP[nonfinite]

She happened to be standing in front of the bank when the robbery occurred.
It just so happens that I have the tool you need to pick that lock.
You didn't happen to see a red glasses case in the conference room, did you?
He just happens to be the most famous tenor in the world!

VerbNet: NM
FrameNet: NM
PropBank: happen.02
WordNet 3.0 Sense Numbers: 3

Sense Number 3: find, come upon, discover

Commentary: Syntax Is: NP1[agent] HAPPEN (UPON) PP{P NP[location]} Includes: HAPPEN UPON

We happened upon a diamond earring on our walk.
If you happen upon Bob tomorrow, can you return this DVD to him?
The chemist happened upon a new synthetic during some experiments.

VerbNet: NM
FrameNet: Becoming_aware
PropBank: happen.03
WordNet 3.0 Sense Numbers: 5