Question

interval larger than an octave

Answer 1

well an octave have 6 notes/pitches between it. An interval on the other hand is like a difference between two pitches.

Answer 2

An interval larger than an octave is often referred to as a Compound Interval. For example, an octave + major 2nd would be called a compound major second. However, you could also simply refer to it as a major ninth. I hope that helps but your question isn't very clear.