to make something continue at the same level, standard, etc.

to keep a building, a machine, etc. in good condition by checking or repairing it regularly

The house is large and difficult to maintain.

to support somebody/something over a long period of time by giving money, paying for food, etc.

Her income was barely enough to maintain one child, let alone three.

to keep stating that something is true, even though other people do not agree or do not believe it

The men maintained (that) they were out of the country when the crime was committed.

It is difficult to maintain that such a harsh punishment was justified.

She has always maintained her innocence.

‘But I'm innocent!’ she maintained.

LEARNit Dictionary