foxfire
Wood exhibiting fungal bioluminescence; torchwood.
uncountable
On the inside is fixed a Barometer, by which he can tell the depth he is under water; a Compass, by which he knows the course he steers. In the barometer and on the needles of the compass is fixed fox-fire, i.e. wood that gives light in the dark.
Where it comes from
Possibly from fox + fire, though the semantic connection is unclear. Alternatively, the first element may be ultimately from Old French fols (“false”), or the term may derive by folk etymology from phosphor.
Adapted from the Wiktionary entry foxfire (CC BY-SA 4.0).