/ Dictionary / Index P pin oak: Meaning and Definition of Find definitions for: pin' oak" Pronunciation: [key] an oak, Quercus palustris, characterized by the pyramidal manner of growth of its branches and deeply pinnatifid leaves. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. pinnule Pinocchio Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language