The figure or symbol 4, or the fourth point/unit in a sequence. The number is 104 – with a four at the end.
A group or unit of four people or things. The four of us went to the concert together.
A playing card with four pips. He drew a four of hearts from the deck.
A hit in cricket that scores four runs, achieved by the ball reaching the boundary after touching the ground. The batsman hit a four to bring up his half-century.