pil·lar

/ˈpılɚ/ noun, pl -lars [count]

1 : a large post that helps to hold up something (such as a roof)

2 : someone who is an important member of a group

— + of

He is a pillar of the church/community.

a pillar of society

3 : a basic fact, idea, or principle of something

— + of

a central pillar of the theory

one of the five pillars of Islam

The right to vote is a pillar of democracy.

4 : something that rises into the air in a tall, thin shape

Pillars of smoke rose from the factory.

a pillar of rock

from pillar to post

chiefly Brit : from one place or one situation to another

His book has been passed from pillar to post, but no one wants to publish it.

He has been running from pillar to post his whole life.

pillar of strength

: someone or something that gives support or help during difficult times

My husband was my/a pillar of strength during my mother's illness.

Religion was his pillar of strength after his wife died.