1.a fundamental principle or practice;
science eroded the pillars of superstition
2.anything tall and thin approximating the shape of a column or tower;
the test tube held a column of white powder
3.a prominent supporter;
he is a pillar of the community
4.a vertical structure standing alone and not supporting anything (as a monument or a column of air)
5.(architeture) a tall cylindrical vertical upright and used to support a structure