What does it mean for a major interval to be raised by half a step?

When a major interval is raised by half a step, it is termed as "augmented." An augmented interval is created by increasing the size of the major interval, which means you are adding an additional half step to its distance. For example, a major third, which spans four half steps, becomes an augmented third by raising it by one additional half step, making it span five half steps.

This concept is key in music theory, as it helps in understanding the relationships between different intervals and how they can be manipulated to create varying harmonic or melodic effects. An augmented interval is often perceived as having a brighter, more intense sound compared to its original major counterpart.