“principle”

The state of organisms preceding their death, characterized by biological processes such as metabolism and reproduction and distinguishing them from inanimate objects; the state of being alive and living.

Diligent inquiry or examination to seek or revise facts, principles, theories, applications, etc. (that are currently available, or that are familiar to oneself).

To know the meaning of; to parse or have parsed correctly; to comprehend.

The source of, or reason for, an event or action; that which produces or effects a result.