build up

build up  {v.}

1. To make out of separate pieces or layers; construct from parts.

Johnny built up a fort out of large balls of snow.

Lois built up a cake of three layers.

2. To cover over or fill up with buildings.

The fields where Tom's father played as a boy are all built up now.

A driver should slow down when he comes to an area that is built up.

3a. To increase slowly or by small amounts; grow.

John built up a bank account by saving regularly.

The noise built up until Mary couldn't stand it any longer.

3b. To make stronger or better or more effective.

Fred exercised to build up his muscles.

Joanne was studying to build up her algebra.

3c.  {informal}

To advertise quickly and publicize so as to make famous.

The press agent built up the young actress.