From the Vocabulary Vaults!

lignify

MEANING:

verb tr.: To convert into wood.
verb intr.: To become wood or woody.

ETYMOLOGY:

From Latin lignum (wood). Ultimately from the Indo-European root leg- (to collect), which is also the source of lexicon, legal, dialogue, lecture, logic, legend, logarithm, intelligent, diligent, sacrilege, elect, and loyal. Earliest documented use: 1828.

USAGE:

When the Cmmdr started out, there was a certain infectious earnestness to his acting, but as he aged, any craft he possessed began to lignify, until his oeuvre resembled a dead forest.