The correct spelling of the word "grinding downs" is [ˈɡraɪndɪŋ daʊnz]. The word "grinding" refers to the action of grinding or crushing something into small particles, while "downs" refers to areas of land that are characterized by low hills or dunes. The "d" in "grinding" is pronounced as a voiced consonant while the "d" in "downs" is pronounced as a voiceless consonant. The combination of these two words creates a compound noun that describes the action of grinding something on a surface characterized by low hills.