An idiom meaning that something is hard to enter or approach; it conveys a feeling of being intimidated or reluctant to visit because the place or relationship feels imposing.
あの料亭は格式が高くて敷居が高いと感じる人も多い。
Many people feel that that ryōtei (high-class restaurant) is intimidating and hard to enter.
彼女の家は有名人がよく来るので、一般の友達には敷居が高い。
Her home often hosts celebrities, so ordinary friends feel it's difficult to visit.
新しいサークルは雰囲気が堅くて、最初は敷居が高かったが、すぐに慣れた。
The new club felt formal and intimidating at first, but I soon got used to it.