WordNet sense 1 (the elastic tension of living muscles, arteries, etc. that facilitate response to stimuli):

tonicity, tonus

WordNet sense 2 (the general atmosphere of a place or situation and the effect that it has on people):

feel, feeling, flavor, look, smell, spirit, flavour

WordNet sense 3 (the quality of a person's voice):

tone of voice

WordNet sense 4 (a notation representing the pitch and duration of a musical sound):

note, musical note

WordNet sense 5 (a musical interval of two semitones):

step, whole step, whole tone

WordNet sense 6 (a steady sound without overtones):

pure tone

WordNet sense 7 ((music) the distinctive property of a complex sound (a voice or noise or musical sound)):

quality, timber, timbre

WordNet sense 8 (a quality of a given color that differs slightly from a primary color):

shade, tincture, tint

WordNet sense 9 (utter monotonously and repetitively and rhythmically):

chant, intone

WordNet sense 10 (vary the pitch of one's speech):

inflect, modulate

WordNet sense 11 (give a healthy elasticity to):

strengthen, tone up