pattern - What is a Bumpy Word™?

_{This is in the spirit of the What is a Word/Phrase™ series started by JLee with a special brand of Phrase™ and Word™ puzzles.}

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If a word has a certain property, I call it a Bumpy Word™.

You can use the examples below to find the property:

$$\begin{array}{|c|c|} \hline \textbf{Bumpy Words™}&\textbf{Not Bumpy Words™}\\ \hline \text{ARMY}&\text{NAVY}\\ \hline \text{BUMPING}&\text{JERKING}\\ \hline \text{CABAL}&\text{CONSPIRACY}\\ \hline \text{CHASER}&\text{PURSUER}\\ \hline \text{COALESCE}&\text{SOLIDIFY}\\ \hline \text{COMPOSITE}&\text{DIVERSE}\\ \hline \text{CRANK}&\text{TURN}\\ \hline \text{CRAZY}&\text{INSANE}\\ \hline \text{EXAMINATION}&\text{TEST}\\ \hline \text{FERAL}&\text{UNCIVILIZED}\\ \hline \text{HIGHER}&\text{GREATER}\\ \hline \text{JUMPING}&\text{LEAPING}\\ \hline \text{ORATOR}&\text{SPEAKER}\\ \hline \text{QUALITATIVE}&\text{SUBJECTIVE}\\ \hline \text{SQUASH}&\text{CRUSH}\\ \hline \text{THRASH}&\text{SPASM}\\ \hline \text{TRUSTING}&\text{BELIEVING}\\ \hline \text{UPWARD}&\text{SKYBOUND}\\ \hline \text{VAULTING}&\text{CAVERNOUS}\\ \hline \text{WELDED}&\text{FUSED}\\ \hline \end{array}$$

For those without MathJax, or if you want to pop this into a spreadsheet, here is a CSV version:

Bumpy™,Not Bumpy™
ARMY,NAVY
BUMPING,JERKING
CABAL,CONSPIRACY
CHASER,PURSUER
COALESCE,SOLIDIFY
COMPOSITE,DIVERSE

CRANK,TURN
CRAZY,INSANE
EXAMINATION,TEST
FERAL,UNCIVILIZED
HIGHER,GREATER
JUMPING,LEAPING
ORATOR,SPEAKER
QUALITATIVE,SUBJECTIVE
SQUASH,CRUSH
THRASH,SPASM

TRUSTING,BELIEVING
UPWARD,SKYBOUND
VAULTING,CAVERNOUS
WELDED,FUSED

Answer

In a word,

If a letter occurs (in the alphabet) later than the previous letter in the word, let us call it a "rise", otherwise, it's called a "fall". Note that the first letter of a word is neither of these.

Then a Bumpy word is

A word in which "rise"s and "fall"s occur alternately.

Example:

A,R(rise),M(fall),Y(rise) | N,A(fall),V(rise),Y(rise).

Why "Bumpy"?

For a Bumpy word, imagine plotting the letter-indexes in the order they occur in the word. For example, "BUMPING" would be plotted as follows:


Alternation between "rise" and "fall" obviously means that the graph is more "uneven" or "bumpy".