Main points

* Ergative verbs are both transitive and intransitive. The object of the transitive use is the subject of the intransitive use, for example: `I opened the door’, `The door opened’.

* A few verbs are only ergative with particular nouns.

* A few of these verbs need an adverbial when they are used without an object.

1 Some verbs can be used as transitive verbs to focus on the person who performs an action, and as intransitive verbs to focus on the thing affected by the action.
When I opened the door, there was Laverne.
Suddenly the door opened.

Note that the object of the transitive verb, in this case `the door’, is the subject of the intransitive verb. Verbs like these are called `ergative’ verbs.

2 Ergative verbs often refer to:

* changes

begin, break, change, crack, dry, end, finish, grow, improve, increase, slow, start, stop, tear

I broke the glass.
The glass broke all over the floor.
The driver stopped the car.
A big car stopped.

* cooking

bake, boil, cook, defrost, fry, melt, roast, simmer

I’ve boiled an egg.
The porridge is boiling.
I’m cooking spaghetti.
The rice is cooking.

* position or movement

balance, close, drop, move, open, rest, rock, shake, stand, turn

She rested her head on his shoulder.
Her head rested on the table.
An explosion shook the hotel.
The whole room shook.

* vehicles

backdrivereversesail
crashflyrun

He had crashed the car twice.
Her car crashed into a tree.
She sailed her yacht round the world.
The ship sailed on Monday.

3 Some verbs can be used in these two ways only with a small set of nouns. For example, you can say `He fired a gun’ or `The gun fired’. You can do the same with other words referring to types of gun, `cannon’, `pistol’, or `rifle’. However, although you can say `He fired a bullet’, you cannot say `The bullet fired’.

catch:belt, cloth, clothing, dress, shirt, trousers
fire:cannon, gun, pistol, rifle
play:guitar, music, piano, violin
ring:alarm, bell
show:anger, disappointment, emotions, fear, joy
sound:alarm, bell, horn

I caught my dress on the fence.
My tights caught on a nail.
A car was sounding its horn.
A horn sounded in the night.

4 A few verbs can be used in both ways, but need an adverbial when they are used without an object.

cleanhandlepolishstain
freezemarksellwash

He sells books.
This book is selling well.
She had handled a machine gun.
This car handles very nicely.