The noun pillar has 5 senses (first 1 from tagged texts)
1. (1) pillar -- (a fundamental principle or practice; "science eroded the pillars of superstition")
2. column, tower, pillar -- (anything tall and relatively thin that approximates the shape of a column or tower; "the test tube held a column of white powder"; "a tower of dust rose above the horizon"; "a thin pillar of smoke betrayed their campsite")
3. pillar, mainstay -- (a prominent supporter; "he is a pillar of the community")
4. column, pillar -- (a vertical cylindrical structure standing alone and not supporting anything (such as a monument))
5. column, pillar -- ((architeture) a tall cylindrical vertical upright and used to support a structure)