Fiddleback is the term often used to describe wavy grain in maple since it's frequently used for you-know-what.

NPR: Excerpt: 'A Splintered History Of Wood'

Quilted figure is revealed when wood with wavy grain is flat-sawn.

NPR: Excerpt: 'A Splintered History Of Wood'

Wavy, ribbon and curly grain are byproducts of spiral grain that reverses itself periodically as a tree grows to produce a thing called interlocked grain.

NPR: Excerpt: 'A Splintered History Of Wood'