The verb βιβρωσκω (bibrosko) means to eat or consume, and stems from the same Proto-Indo-European root "gwerh-", meaning to eat or devour, that gave Latin the verb voro and hence English words like devour and voracious and the "-vorous" extension of words like carnivorous. Our verb is actually quite rare, as it's used in the New Testament in John 6:13 only.

The more common verb for to eat is φαγω (phago), but there doesn't seem to be a significant difference between these two verbs, except perhaps that our verb βιβρωσκω (bibrosko) emphasizes the entire process of consumption and digestion, down to the defecation of the wastes (Mark 7:19). The in the New Testament unused noun βρωμος (bromos) describes a noisome smell or stink, obviously related to either fecal matter or a rotting pile of organic matter being consumed by bacteria and such.

Note that the conspicuous use of our verb in John 6:13 (where the disciples gather the remaining pieces of bread into twelve baskets), deliberately suggests that the disciples might have been gathering, well, chunks of digested bread rather than uneaten ones, which is of course hilarious (also because honey is produced from nectar in the bee's complex digestive track; see our article on the name Deborah for the significance of this). For more deliberate hilarity in the gospel of John, and the reason why John is hilarious, see our riveting article on χξς (ch-x-s), meaning six hundred and sixty six.

From this verb come:

The verb τρωγω (trogo) also means to eat or consume (or eat holes into), but occurs in the classics predominantly in perfect passive forms: things "having been eaten" are not only things that are proven to be edible, but also things (and people) that are thoroughly worn out as if nibbled from on all sides. From this verb also comes the noun τρωγλη (trogle), hole, from which comes the word troglodyte, hole-plunger: mice, foxes, serpents, cave-men. The noun τρωγαλια (trogalia) described the nuts and fruits that were commonly served as dessert after a banquet: things to nibble on, or perhaps things to fill the final holes with.

The use of this specific verb indicates that the people before the flood weren't merely eating and drinking, but rather exhausting their world and stuffing their bellies. In a wryly similar way, Jesus wants the knowledge of natural law to be applied exhaustively (John 6:54-58; see John 1:18, Romans 1:20, Hebrews 1:3).

It's not clear where this verb comes from, but a candidate is the same huge Proto-Indo-European root that also yielded the verb τριβω (tribo), to rub or wear smooth, and thus the noun τριβος (tribos), smoothness, and particularly the smoothness of a highway that's been worn flat from the many feet that walked it (Matthew 3:3). This verb is thought to be related to τρωω (troo) or τρωσω (troso), to wound.

Our verb τρωγω (trogo), to consume, is used 6 times; see full concordance.