close in

present singular third person closes in · participle present closing in · participle past closed in · past closed in

1. transitiveTo enclose, lock up inside something.
2. intransitiveTo come or approach nearer to someone being pursued.

   The police had not yet caught the thieves, but were closing in.

   1 more example

   Keep refining your estimate, and you will gradually close in on the right answer.

3. To become closer, surround.

   Then we pass through Bebington station, and, entering a cutting, become aware of the usual signs of approach to an urban area—buildings closing in, an all-round increase in smokiness, and the application of brakes.

   1955 January, R. S. McNaught, “From the Severn to the Mersey by Great Western”, in Railway Magazine, page 21