Definitions
1.nounA large post, often used as supporting architecture.
2.nounSomething resembling such a structure."a pillar of smoke"
3.nounAn essential part of something that provides support."He's a pillar of the community."
4.nounA portable ornamental column, formerly carried before a cardinal, as emblematic of his support to the church.
5.nounThe centre of the volta, ring, or manege ground, around which a horse turns.