Defn: A medicine that increases the srength, and gives vigor of action to the system. Tonic sol-fa (Mus.), the name of the most popular among letter systems of notation (at least in England), based on key relationship, and hence called "tonic." Instead of the five lines, clefs, signature, etc., of the usual notation, it employs letters and the syllables do, re, mi, etc., variously modified, with other simple signs of duration, of upper or lower octave, etc. See Sol-fa.
TONICAL
Ton"ic*al, a.
Defn: Tonic. [R.] Sir T. Browne.
TONICITY
To*nic"i*ty, n. (Physiol.)
Defn: The state of healty tension or partial contraction of muscle fibers while at rest; tone; tonus.
TONIGHT
To*night", adv. Etym: [Prep. to+night]
1. On this present or coming night.
2. On the last night past. [Obs.] Shak.
TONIGHT
To*night", n.
Defn: The present or the coming night; the night after the present day.