You searched for: “a plumb
aplomb, a plum, a plumb
aplomb (uh PLOM, uh PLUM) (pronoun)
Confidence, skill, and poise; especially, in difficult or challenging circumstances: "A good hostess can handle an embarrassing situation with great aplomb."
a plum (uh PLUM) (pronoun)
A round or oval smooth-skinned fruit, usually red or purple, containing a flattened pit: "Gwendolyn gave Kirk a plum to eat which he thought was delicious."
a plumb (uh PLUM) (pronoun)
1. As a noun, a weight, usually made of lead, attached to a line and used to find the depth of water or to verify a true vertical alignment: "Austin used a lead ball, a plumb, attached to a line so he could determine the vertical accuracy of the building's walls."
2. Also, as a verb, to examine something in a careful and complete way in order to understand it: "The book strives to plumb the complexities of human relationships."

"As a psychologist, Wallace spent several years trying to plumb the minds of criminals."

The surveyors had to improvise when they needed a plumb and used a ripe plum attached to a string as a plumb for surveying the field.

At the end of the day, with great aplomb, one of the surveyors ate the plum.