The Word is:”the”
1. denoting one or more people or things already mentioned or assumed to be common knowledge.
“what’s the matter?”
denoting a disease or affliction.
“I’ve got the flu”
“dish of the day”
used instead of a possessive to refer to someone with whom the speaker or person addressed is associated.
“I’m meeting the boss”
“the Johnsons were not wealthy”
2. used to point forward to a following qualifying or defining clause or phrase.
“the fuss that he made of her”
“George the Sixth”
3. used to make a generalized reference to something rather than identifying a particular instance.
“he taught himself to play the violin”
“they placed the African elephant on their endangered list”
“they are trying to accomplish the impossible”
“they can do 120 miles to the gallon”
4. enough of (a particular thing).
“he hoped to publish monthly, if only he could find the money”
5. (pronounced stressing ‘the’) used to indicate that someone or something is the best known or most important of that name or type.
“he was the hot young piano prospect in jazz”
6. used adverbially with comparatives to indicate how one amount or degree of something varies in relation to another.
“the more she thought about it, the more devastating it became”
“commodities made all the more desirable by their rarity”
Source credit: Google