Seasoned wood (moisture content)
Seasoned wood is firewood dried to below roughly 20% moisture content — the threshold at which a modern stove can burn it cleanly and efficiently. Fresh-cut ("green") wood is 35–60% water, and burning it wastes heat boiling water while producing smoke and creosote.
Seasoning takes time: split and stacked off the ground with the top covered, most hardwoods need 6–12 months and dense species like oak often need two summers. Wood dries from the cut ends, so splitting is what actually exposes the interior.
A $20–40 pin moisture meter ends the guesswork: split a piece and measure the fresh inner face — the outside of a rained-on but seasoned split reads wet while the inside is fine, and vice versa for surface-dry green wood.