grub

\ \ [13] Grub ‘dig’ comes ultimately from prehistoric Germanic *grub-, perhaps via Old English *grybban, although no record of such a verb has actually come down to us (the related Germanic *grab- gave English grave, while a further variant *grōb- produced groove [15]).

\ \ The relationship of grub ‘dig’ to the various noun uses of the word is far from clear. Grub ‘larva’, first recorded in the 15th century, may have been inspired by the notion of larvae digging their way through wood or earth, but equally it could be connected (via the idea of ‘smallness’) with the contemporary but now obsolete grub ‘short, dwarfish fellow’ – an entirely mysterious word. Grub ‘food’, which dates from the 17th century, is usually said to have been suggested by birds’ partiality for grubs or larvae as part of their diet. And in the 19th century a grub was also a ‘dirty child’ – perhaps originally one who got dirty by digging or grubbing around in the earth – which may have been the source of grubby ‘dirty’ [19].

\ \ Cf.⇒ GRAVE, GROOVE