lignum

Lignum, ligni is second declension neuter and means wood as material or as fuel. The plural ligna almost always means firewood specifically, a load of logs rather than an abstract quantity of timber. For the living tree Latin uses arbor, and for a forest silva; confusing lignum with either is the usual beginner's slip, since English "wood" covers all three.

In Christian Latin lignum acquires a heavy second life as the Cross, lignum vitae, "the tree of life", and the wood of the crucifixion, so an ecclesiastical text talking about lignum is often not talking about carpentry. Italian legno and Spanish leno continue it, and English took ligneous and lignite.