To consume something means to use it up or eat it completely.
When we talk about consuming food, we usually think of eating it, but the word has a broader meaning. When you watch TV all day and don't do anything else, that's also a way of consuming time. You're using it up on one activity instead of doing something else with it. Some people worry about over-consuming resources like water or energy, which means they use too much of them.
How common is "consume"?
Word consume is considered uncommon in modern English. It has a balanced usage among all categories: speech, fiction, newspapers and academic texts.
Definitions
verb
(transitive) To use up.
Example: The power plant consumes 30 tons of coal per hour.
(transitive) To eat.
Example: Baby birds consume their own weight in food each day.
(transitive) To completely occupy the thoughts or attention of.
Example: Desire consumed him.
(transitive) To destroy completely.
Example: The building was consumed by fire.
(intransitive, obsolete) To waste away slowly.
(economics, transitive, intransitive) To trade money for good or services as an individual.
Example: In a materialistic society, individuals are taught to consume, consume, consume.
(transitive) To absorb information, especially through the mass media.
Example: The Internet has changed the way we consume news.