oaken adj.

"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]

suffix added to nouns to produce adjectives meaning "made of, of the nature of" (such as golden, oaken, woolen), corresponding to Latin -anus, -inus, Greek -inos; from Proto-Germanic *-ina- (from PIE *-no-, adjectival suffix).

Common in Old, Middle, and early Modern English: e.g. fyren "on fire; made of fire," rosen "made or consisting of roses," hunden "of dogs, canine," beanen "of beans," baken "baked," breaden "of bread;" Wycliffe has reeden made of or consisting of reeds." The few surviving instances are largely discarded in everyday use, and the simple form of the noun doubles as adjective (gold ring, wool sweater). Some are used in special contexts (brazen, wooden).