Flagpole Interactions Definition:

For cyclohexane, flagpole interaction is the steric interactions that occur between the flagpole hydrogen atoms in a boat conformation.

Flagpole Interactions Explained:

The flagpole interactions are specifically for the hydrogen or substituents that take up the two flagpole positions. Steric interactions between the flagpole molecules lead to additional strain because of which the energy level of the molecule is raised. This is not the lowest energy conformation.