Webster’s Revised Unabridged Dictionary · 1913
Lignify
Lig′ni·fy (-fī), v. t. [imp. & p. p. Lignified (-fīd); p. pr. & vb. n. Lignifying (- fī′ĭng).] [L. lignum wood + -fy: cf. F. lignifier.] (Bot.) To convert into wood or into a ligneous substance.
Lig′ni·fy, v. i. (Bot.) To become wood.