Synonyms of up-and-down

1 Syllable
yoyo
2 Syllables
seesaw, bobbing, yo-yo
3 Syllables
mercurial, vertical, hot-and-cold, unprompted, uneven, quicksilver
4 Syllables
vacillating, impulsive, volatile, bubbleheaded
5 Syllables
unmeditated, perpendicular