verb. Present participle of nest.

noun. The process by which a bird nests.

noun. The enclosure of one loop, block, etc. of code inside another.

"But I prefer the term nesting rhymes because the words nest one inside the other like Russian wooden dolls."

arresting  attesting  besting  breasting  contesting  

abiding  abode  altricial  anserine  anserous  

nest