What does line of force mean?

Here's a list of possible definitions for the term line of force:

Princeton's WordNet

1. line of force, field line(noun)

an imaginary line in a field of force; direction of the line at any point is the direction of the force at that point

Wiktionary

1. line of force(Noun)

an imaginary line in a field of force, whose tangent at any point gives the direction of the field at that point and whose number through unit area perpendicular to the field represents its intensity

Freebase

1. Line of force

A line of force in Faraday's extended sense is synonymous with Maxwell's line of induction. According to J.J. Thomson, Faraday usually discusses lines of force as chains of polarized particles in a dielectric, yet sometimes Faraday discusses them as having an existence all their own as in stretching across a vacuum. In addition to lines of force, J.J. Thomson—similar to Maxwell—also calls them tubes of electrostatic inductance, or simply Faraday tubes. From the 20th century perspective, lines of force are energy linkages embedded in a 19th century unified field theory that led to more mathematically and experimentally sophisticated concepts and theories, including Maxwell's equations, electromagnetic waves, and Einstein's relativity.

Numerology

1. Chaldean Numerology

The numerical value of line of force in Chaldean Numerology is: 9

2. Pythagorean Numerology

The numerical value of line of force in Pythagorean Numerology is: 9