threshold (amount, dose, etc.)
 threshold (amount, dose, etc.)
 window-sill;  window-ledge
 having a high threshold (for entry);  difficult to approach;  feeling awkward to go to (of someone's home)
 having a high threshold (for entry);  difficult to approach;  feeling awkward to go to (of someone's home)
 threshold gate;  threshold element
 threshold gate;  threshold element