Stringpiece
Pronunciation : String"piece`, n. (Arch.) (a) A long piece of timber, forming a margin or edge of any piece of construction; esp.: (b) One of the longitudinal pieces
Part of Speech : supporting
Definition :
the treads and rises of a flight or run of stairs.
Source : Webster's Unabridged Dictionary, 1913
Merriam-Webster's Everyday Language Reference Set: Includes: The Merriam-Webster Dictionary, The Merriam-Webster Thesaurus, and The Merriam-Webster Vocabulary Builder