In Tetris, a game named for the Greek word for 4, every shape in the game is formed of 4 blocks each. 4 represents the number of Justices on the Supreme Court of the United States necessary to grant a writ of certiorari (i.e., agree to hear a case; it is one less than the number necessary to render a majority decision) at the courts current size. Number Four is a character in the book series Lorien Legacies. In the performing arts, the fourth wall is an imaginary barrier which separates the audience from the performers, and is "broken" when performers communicate directly to the audience. In music
In written music, common time is constructed of four beats per measure and a quarter note receives one beat. In popular or modern music, the most common time signature is also founded on four beats, i.e., 4/4 having four quarter note beats. The common major scale is built on two sets of four notes (e.g., CDEF, GABC), where the first and last notes create an octave interval (a pair-of-four relationship). The interval of a perfect fourth is a foundational element of many genres of music, represented in music theory as the tonic and subdominant relationship. Four is also embodied within the circle of fifths (also known as circle of fourths), which reveals the interval of four in more active harmonic contexts. The typical number of movements in a symphony. The number of completed, numbered symphonies by Johannes Brahms.
Sinusoidal hemangioma is a condition, by something of a misnomer, a term for a lesion that is a vascular malformation with various clinical presentations. This condition may present as nodules, often in the breast area or extremities, or as large firm bulging facial masses beneath normal-appearing skin; the latter have an aggressive and invasive course. See also
Sinus pericranii
List of cutaneous conditions


== References ==