food, especially plain or simple food, or a thick soft larva of an insect like a beetle.
As a noun meaning insect larva, from Old English 'grubbe' meaning something that grows underground. The slang meaning 'food' comes from American English (1600s), possibly because grubs are found in the ground and are associated with digging.
When cowboys and miners called food 'grub,' they were being poetic—just as you dig for edible grubs in the soil, you dig or work for your meals! The word captures the effort and earthiness of frontier survival.
Complete word intelligence in one call. Free tier — 50 lookups/day.