[rooz; Scot. also rœz]Chiefly Scot.
Origin of roose
1150–1200; Middle English rosen < Old Norse hrōsa to praise
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Word Origin and History for roosing
c.1200, "to boast;" c.1300, "to praise," Scottish dialect, from Old Norse hrosa "to boast of, to praise." Related: Roosed; roosing. Also as a noun from c.1200.
Online Etymology Dictionary, © 2010 Douglas Harper