The Practice of Poetry: Writing Exercises From Poets Who Teach, contains a number of prompts and writing exercises, including this one entitled Emotion/Motion/Ocean/Shun. Here's what Susan Mitchell writes:
If you read the title of this exercise aloud, you will hear a quadruple rhyme. But if you examine the words themselves, you will notice that there is something special about this rhyme scheme. The sound shun is contained in ocean, the sounds of both shun and ocean in motion, and shun, ocean and motion can all be folded into emotion. Such a rhyme scheme, which incidentally was favored by the seventeenth-century poet George Herbert, is called diminishing rhyme because the rhyme words get smaller as you move from emotion to shun. But I prefer the term nesting rhymes because the words nest one inside the other like Russian wooden dolls.
Here is an example of this form from the George Herbert poem "Paradise".
I bless Thee, Lord, because I grow
Among the trees, which in a row
To Thee both fruit and order ow
Read the poem in its entirety.
So, that's it. Your challenge is to write a poem that uses diminishing rhyme. Won't you join us? Please share a link to your poem or the poem itself in the comments.