Energy that is derived from traditional resources, such as coal, oil, natural gas, and nuclear power, which are seen by some as environmentally unfriendly. If we're going to keep our planet clean, we need to move away from brown energy and invest in renewable resources, such as wind and solar.

Someone who is exceptionally energetic, alert, productive, or hyperactive. My kids are always such bundles of energy first thing in the morning. Susan is a bundle of energy! She's already finished two of her essays today and is beginning to work on a third.

A useless, vain, or redundant effort or action. It turns out the boss had already chosen a direction for the project, so my presentation was a complete waste of energy.

In science, energy converted into a form that is unavailable for work. Today, we'll be studying the unavailable energy in this system.

vulgar slang Confidence and self-assuredness, especially when exuded in a calm or quiet manner. Although the term alludes to the confidence that may result from having a large penis, the phrase is not necessarily literal and is not exclusively applied to men. Commonly abbreviated with the initialism "BDE." John is a guy who has the confidence to show his emotions without hesitation or embarrassment—that's total big dick energy, if you ask me. A: "I can't believe you were able to negotiate such a big raise. You've got some serious big dick energy, girl." B: "What? I just know I'm worth more than they were paying me."