The phrase "major pillar" means an important and strong support or foundation, usually referring to a key aspect of something or someone's position or structure that holds it up. Full definition
Alongside the UN and the SARC, the International Committee of the Red Cross is the other major pillar of international humanitarian action that will be central to a humanitarian strategy in Syria. (blog.politics.ox.ac.uk)
The other major pillar of the reform is the cuts that have been enacted for individual income earners, with middle - class taxpayers earning between $ 19,050 and $ 77,400 per year receiving a cut in tax from 15 to 12 percent. (internationalbanker.com)