main; principal; major; primary

The water mains burst due to the earthquake.

In some rural areas, the Internet is important for agricultural information, as well as being particularly useful for the purposes of agricultural production technologies and pricing.

One of the major Internet search engines states that ‘Fast is better than slow’.

The main duty of a priest is to preach in church.

Nearly all siheyuans had their main buildings and gates facing south for better lighting, so a majority of hutongs run from east to west.