(physics) a thermodynamic quantity equivalent to the capacity of a physical system to do work; the units of energy are joules or ergs
"energy can take a wide variety of forms"
enterprising or ambitious drive
"Europeans often laugh at American energy"
an imaginative lively style (especially style of writing)
"his writing conveys great energy"
"a remarkable muscularity of style"
the federal department responsible for maintaining a national energy policy of the United States; created in 1977
"The new bill requires strict oversight from the Department of Energy to ensure our transition to renewable sources aligns with the 1977 mandate."
The impetus behind all motion and all activity.
"The sudden burst of energy from the explosion sent debris flying in every direction."
In plain English: Energy is the power needed to make things move, change, or happen.
"She has so much energy that she never seems to get tired during the day."
Usage: Use "energy" to describe the capacity to do work or the vigor with which someone performs an activity, such as having the energy to finish a long day. Avoid using it as a verb; instead of saying "he is energetic," simply state that he has energy.
The word energy comes from the Ancient Greek enérgeia, meaning "activity," and entered English via Middle French and Late Latin. Its specific scientific sense referring to a physical property was coined by Thomas Young in 1802.