alburnum, i, n. [albus],
the soft , thin , white layer between the bark and wood of trees , sap-wood , alburnum , Plin. 16, 38, 72, § 182.
·noun The white and softer part of wood, between the inner bark and the hard wood or duramen; sapwoo...
Webster's Dictionary of the English Language
The sap-wood of timber, commonly termed the slab-cuts. ...
The Sailor's Word-Book