live-oak (n.)

1540s, "having life, not dead," a shortening of alive (q.v.). From 1610s of fire, coal, etc., "burning, glowing;" 1640s of things, conditions, etc., "full of active power;" sense of "containing unspent energy or power" (live ammunition) is from 1799.

Meaning "in-person, not recorded" (of performance) is attested by 1917. Live wire is attested from 1890, "circuit through which an electric current is flowing;" figurative sense of "active person" is from 1903. Jocular real live "genuine" is from 1887. The older adjective is lively.

A GRIM RECORD — The death harvest of the "live wire" and "third rail" goes right on. It is not governed by seasons nor, qualified by time. It is the ubiquitous epidemic of electricity, defiant of doctors and ruthless as fate. [The Insurance Press, Aug. 22, 1900]

"tree or shrub of the genus Quercus," Middle English oke, from Old English ac "oak tree" and in part from cognate Old Norse eik, both from Proto-Germanic *aiks (source also of Old Saxon and Old Frisian ek, Middle Dutch eike, Dutch eik, Old High German eih, German Eiche, Swedish ek, Danish eg), a word of uncertain origin with no certain cognates outside Germanic.

The usual Indo-European base for "oak" (*deru-) has become Modern English tree (n.). In Greek and Celtic, meanwhile, words for "oak" are from the Indo-European root for "tree." All this probably reflects the importance of the oak, the monarch of the forest, to ancient Indo-Europeans. Likewise, as there were no oaks in Iceland, the Old Norse word eik came to be used by the viking settlers there for "tree" in general.

In English the word is used in Biblical translations to render Hebrew elah (probably usually "terebinth tree") and four other words. The form in Middle English was very uncertain (oc, oek, hokke, ake, eoke, aike, hock, etc.). Oak-gall "excrescence produced by an oak tree in reaction to insects," used in making ink, is by 1712.

                            Jove's own tree,

That holds the woods in awful sovereignty,

Requires a depth of lodging in the ground ;

High as his topmost boughs to heaven ascend,

So low his roots to hell's dominion tend.

[Dryden, translating Virgil]