eat up is a verb meaning "finish eating all the food on one's plate or on the table". It carries 3 recorded senses.
finish eating all the food on one's plate or on the table
“She polished off the remaining potatoes”
use up (resources or materials)
“this car consumes a lot of gas”
“We exhausted our savings”
“They run through 20 bottles of wine a week”
enclose or envelop completely, as if by swallowing
“The huge waves swallowed the small boat and it sank shortly thereafter”
Definitions, synonyms and semantic relations for eat up come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.