Meaning of “start” - Learner’s Dictionary

start

verb uk us /stɑːt/
BEGIN DOING [ I, T ]

A1 to begin doing something:

[ + doing sth ] He started smoking when he was eighteen.
[ + to do sth ] Maria started to laugh.
We start work at nine o'clock.
BEGIN HAPPENING [ I, T ]

B1 to begin to happen or to make something begin to happen:

The programme starts at seven o'clock.
Police believe the fire started in the kitchen.
BUSINESS [ I, T ] (also start up)

B2 If a business, organization, etc starts, it begins to exist, and if you start it, you make it begin to exist:

She started her own computer business.
A lot of new restaurants have started up in the area.
CAR [ I, T ] (also start up)

B2 If a car or engine starts, it begins to work, and if you start it, you make it begin to work:

The car won't start.
Start up the engine.
to start with

used to talk about what a situation was like at the beginning before it changed:

I was happy at school to start with, but later I hated it.

used before saying the first thing in a list of things:

To start with, we need better computers. Then we need more training.
MOVE SUDDENLY [ I ]

(Definition of “start verb” from the Cambridge Learner’s Dictionary © Cambridge University Press)