エネルギーenerugii

1. noun, physicsenergy
   熱ねつはエネルギーの一種いっしゅである。↗

   Heat is a form of energy.
2. nounenergy; strength; power; stamina; get-up-and-go
   僕ぼくはエネルギーを使い果つかいはたした。↗

   I have exhausted my energy.
3. nounenergy source; energy resource
4. nounfood energy; calories
   カロリーは食物しょくもつが持もつエネルギーを正確せいかくに示しめす尺度しゃくどである。↗

   The calorie is an exact measure of the energy in food.

• SynonymエナジーNeutralLoanword seen mostly in drinks and product names like 「エナジードリンク」; in everyday speech, say 「エネルギー」.
• Synonym活力かつりょくNeutralThe driving force behind activity, as in 「活力を与える」; used of society, the economy and people, but not of physical energy.
• Synonym精力せいりょくNeutralA person's energy for getting things done, and also sexual vigor, as in 「精力的に働く」; not used for physical energy.
• Synonym気力きりょくNeutralThe mental strength to keep going, as in 「気力がない」; the emphasis is on willpower.
• Synonym力ちからNeutralStrength or ability, as in 「力がある」; the broadest of these words, while 「エネルギー」 leans toward energy and drive.
• Synonym生気せいきWrittenWritten/formal: signs of life and vitality, as in 「生気がない顔」; describes the state of people or things.
• Synonym活動力かつどうりょくWrittenWritten/formal word for the drive to act; in daily conversation use 「活力」 or 「元気」 instead.
• RelatedバイタリティNeutralLoanword for vitality and abundant drive, as in 「バイタリティがある」; mostly describes people.
• Related元気げんきNeutralBeing lively and in good health, as in 「元気が出る」; very common in speech, while 「エネルギー」 also covers physical energy.
• Related活気かっきNeutralThe bustle and liveliness of a place or atmosphere, as in 「活気のある街」.
• Related意気いきWrittenWritten/formal: fighting spirit or zeal, mostly in 「意気込み」「意気投合」; seldom used on its own.
• Related力ちからNeutralStrength or ability, as in 「力がある」; the broadest of these words, while 「エネルギー」 leans toward energy and drive.

「エネルギー」 covers physical energy and also drive or stamina. For a person's stamina say 「精力」 or 「バイタリティ」; for the vitality of society or an economy, 「活力」; for a lively place, 「活気」; for the will to persevere, 「気力」; in everyday talk, 「元気」 is the usual word.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 仕事しごとをすることができる量りょう・能力のうりょく。
2. 人間にんげんの活動かつどうの力ちから。