《architecture》threshold (esp. one with grooves for sliding doors); sill
「閾」 has another reading with different meanings.
threshold; limen
lintel (esp. one with grooves for sliding doors)
敷居が高くて入りにくい。
The threshold is high, making it hard to enter.
古い家は敷居が低い。
Old houses have low thresholds.
敷居をまたいで部屋に入った。
I stepped over the threshold into the room.