Worry, anxiety, or concern; something that weighs on one's mind.
試験の結果がまだ出ていなくて気がかりだ。
I'm worried because the exam results haven't come out yet.
家族の健康が一番の気がかりだ。
My family's health is my biggest concern.
彼の返事がないのが気がかりで仕方ない。
I can't help worrying that he hasn't replied.