1.
to begin to move :
The horse started off at a steady trot.
2.
to begin happening; to begin doing sth :
The discussion started off mildly enough.
3.
to begin by doing or being sth :
Let's start off with some gentle exercises.
We started off by introducing ourselves.
[+ adj ]
The leaves start off green but turn red later.
[+ -ing ]
I started off working quite hard, but it didn't last.