o, e, n, p, t, u are letters that make 'tone up'
tone, ton, up, one, on, NE, Ne are words within 'tone up'
1 possible definitions for 'tone up'
Under this definition, tone up is a verb and has the following properties:
tone, strengthen have the same meaning as 'tone up'
'tone up' can be a type of exercise, work out.
tonicity, tonus, tone are derivatives of 'tone up'.