ergative phrasal verb block
If you block
or if it blocks up
, it is blocked completely so that nothing can get
'Any holes in the kitchen where the mice are getting through?'—'I've blocked them
Powdering a sweaty nose will only block up the pores and make the skin more uncomfortable.
With this disease the veins in the liver can block up, and all sorts of damage follows.
COBUILD Advanced English Dictionary. Copyright © HarperCollins Publishers