All 5 Uses

petty
in
Snow Falling on Cedars
(Edited)

Ishmael Chambers, in the last light of day, found himself seated in the office of the lighthouse chief petty officer, a large man named Evan Powell.
Chpt 23 *

petty officer = non-commissioned officer
Petty Officer Powell kept an immaculate desk—a calendar blotter, twin upright pen stands, a nearly full ashtray, a telephone.
Chpt 23
"We do a lot of record keeping," Petty Officer Powell replied.
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Petty Officer Powell fell forward in his chair and carefully snubbed out his cigarette.
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"This man here is Ishmael Chambers," Petty Officer Powell explained.
Chpt 23

Definitions:

(1) (petty as in: a petty crime)
of less importance -- at times implying insignificance
(2) (petty as in: don't be petty)
unpleasantly focusing on an unimportant flaw; or attempting to make someone suffer for an unimportant wrong
(3) (petty as in: petty officer)
a non-commissioned officer

Petty officer typically refers to a Navy or Coast Guard officer who is subordinate to commissioned officers and chief petty officers.
(4) (meaning too rare to warrant focus)