1630s, from Latin fluctuatus, past participle of fluctuare "to undulate" (see fluctuation). Related: Fluctuated; fluctuates; fluctuating.
fluctuate fluc·tu·ate (flŭk'chōō-āt')
v. fluc·tu·at·ed, fluc·tu·at·ing, fluc·tu·ates
To vary irregularly.
To rise and fall in waves; undulate.