Definition of "Plum" :

noun: a highly desirable position or assignment

"A political plum."

noun: any of numerous varieties of small to medium-sized round or oval fruit having a smooth skin and a single pit

noun: any of several trees producing edible oval fruit having a smooth skin and a single hard stone

adverb: completely; used as intensifiers

"I'm plumb (or plum) tuckered out."

adverb: exactly

"Fell plumb in the middle of the puddle."