Incomplete combustion: a state in which fuel does not burn completely, producing smoke and possibly carbon monoxide in engines or furnaces.
古いストーブでは不完全燃焼が起きて一酸化炭素中毒の危険がある。
Old stoves can cause incomplete combustion, posing a risk of carbon monoxide poisoning.
エンジンが調子悪いと燃焼が不完全になり、出力が落ちる。
When an engine is in poor condition, combustion can be incomplete and power decreases.
燃焼効率を上げるために空気供給を調整して不完全燃焼を防ぐ。
To improve combustion efficiency, adjust air supply to prevent incomplete combustion.
Figuratively, being unsatisfied because one did not achieve or do one's best; the feeling of having an incomplete or unfulfilled outcome.
試合は勝ったが内容が悪くて不完全燃焼の気分だ。
Although we won the match, the performance was poor and I feel unsatisfied.
志望校に落ちてしまい、不完全燃焼のまま卒業した。
I failed to get into my desired school and graduated with a feeling of unfinished business.
練習は十分だったのに本番で不完全燃焼して悔しい。
Even though I practiced enough, I failed to perform fully on the day and feel frustrated.