MISTERIOSO

məˌstirēˈō(ˌ)sō, (ˌ)miˌs-, -)zō adverb (or adjective)

Etymology: Italian, mysterious, from mistèrio, mistèro mystery (from Latin mysterium ) + -oso -ose (from Latin -osus ) — more at mystery

: in a mysterious manner — used as a direction in music