The crossword solution for the term 'Makes Firmer' is 'Tones'. The term 'tones' can refer to a variety of different things. In music, tones are the specific pitches of notes that create melodies and harmonies. In art, tones are the shades of colors used to create a painting or drawing. In photography, tones are the range of light and dark values in an image. In fitness, tones refer to the strengthening of muscles. In all cases, the term 'tones' implies making something firmer or stronger.