sink in
US /sɪŋk ɪn/
UK /sɪŋk ɪn/

1.
to be fully understood or realized
:
•
It took a while for the news to really sink in.
•
Let what I said sink in before you respond.
2.
to move downwards into a surface or substance
:
•
The heavy rain caused the water to sink in quickly.
•
The mud was so soft that my boots started to sink in.