English: what is a bollard?

Self-tutoring with vocabulary: the tutor mentions bollard.

The following is according to my understanding.

A bollard is one of those pillars one sees preventing vehicles from passing certain points. They can be used to stop vehicles from being able to drive certain courses, or else to prevent vehicles crashing into sensitive installations. Typically they are around hip height and encased in concrete.

Apparently, marine-wise, a bollard is a post on a dock – or boat – used for tying a boat to a dock.

Source:

reliance-foundry.com