hunker down is a verb meaning "sit on one's heels". It carries 3 recorded senses.
take shelter
“During the sandstorm, they hunkered down in a small hut”
hold stubbornly to a position
“The wife hunkered down and the husband's resistance began to break down”
Definitions, synonyms and semantic relations for hunker down come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.