1) Fluctuating 2) Undulating 3) Unstable 4) Varying 
• (a.) Floating on the waves. • (a.) Moving like a wave; wavering • (a.) showing undulation or fluctuation; as, a fluctuant tumor.
A wave like motion that is felt when a fluid containing structure is palpated. ... (27 Sep 1997) ... 
Fluc'tu·ant adjective [ Latin fluctuans , present participle of fluctuare . See Fluctuate .] 1. Moving like a wave; wavering ; (Medicine) showing undulation or fluctuation; as, a fluctuant tumor. 2. Floating on the waves. [ Obsolete] Bacon....
fluctuating; varying; unstable. · undulating; moving or seeming to move in waves.