"Responsive" is the word describing reacting quickly and positively.
Glide would be a word that means "to move in an easy way."
Ire is a three letter word for spleen.
Cage is a four-letter word that starts with c and means cell. Or case! Or the 5 letter word Crypt!
The 6-letter word for getting bigger is "grow."
to move quickly.
If you mean "jerk" as in the verb "to pull, move quickly, twitch," the word "vellicate" is a synonym.
Rush? Run? Hurry?
A three letter word for writing quickly is to jot.
estuary
The state of matter that flows freely is liquid.
nimble the word that means to write quickly is bust to move it baby! Scribble may be the word you are thinking of.
quickly
agility
Speed
Agility.
potato