A rhyme inside a single line or between internal parts of different lines (middle rhyme).
Divide the line and find rhymes inside ('I hit the road, I hit a low, I hit the note.'). Schemes can be written with spaces/commas.
Increases density of sound structure, technical skill, and flow. Classic example: Edgar Allan Poe in 'The Raven'.
Poe: 'Once upon a midnight dreary, while I pondered, weak and weary.' The 'dreary/weary' internal rhyme.