heartwood

Definition of Heartwood in English :

1. duramen, heartwood

the older inactive central wood of a tree or woody plant; usually darker and denser than the surrounding sapwood

WordNet Lexical Database for English. Princeton University. 2010.

Heartwood

noun

the central core of dark hard wood in tree trunks, consisting of non-functioning xylem tissue that has become blocked with resins, tannins, and oils

Compare sapwood

noun

the hard, nonliving, older wood at the core of a tree trunk, usually dark in color and impervious to air and water; duramen

n.

The older, nonliving central wood of a tree or shrub, usually darker and harder than the younger sapwood. Also called duramen.