"exceed in any excess of evil," from Shakespeare's it out-Herods Herod in Hamlet's instruction to the players in "Hamlet" Act III, Scene II. Shakespeare used the same construction elsewhere ("All's Well that Ends Well" has out-villain'd villany). The phrase reflects the image of Herod as stock braggart and bully in old religious drama. The form of the phrase was widely imitated 19c. and extended to any excessive behavior.
Oh, it offends me to the soul to hear a robustious periwig-pated fellow tear a passion to tatters, to very rags, to split the ears of the groundlings, who for the most part are capable of nothing but inexplicable dumb-shows and noise: I would have such a fellow whipped for o'erdoing Termagant; it out-herods Herod: pray you, avoid it. ["Hamlet"]
"a cave, cavern, a vault," c. 1300, from Old French spelonque (13c.) or directly from Latin spelunca "a cave, cavern, grotto," from Greek spelynx (accusative spelynga, genitive spelyngos) "a cave, cavern," from spelos "a cave." An adjective, speluncar "of a cave" is recorded from 1855.
c. 1400, "full of caverns," from Latin cavernosus "full of cavities" (source also of Italian cavernoso, French caverneux), from caverna (see cavern). In English, the meaning "full of cavities, porous" is from 1590s. The meaning "deeply hollowed out" is recorded from 1830.
"picturesque cavern or cave," 1610s, from Italian grotta, earlier cropta, a corruption of Latin crypta "vault, cavern," from Greek krypte "hidden place" (see crypt). Terminal -o may be from its being spelled that way in many translations of Dante's "Divine Comedy."
"a cave bug; one who explores caves as a hobby," 1942, agent noun formed from obsolete spelunk "cave, cavern." The verb spelunk "explore caves" and the verbal noun spelunking are attested from 1946 and appear to be back-formations.
early 15c., cripte, "grotto, cavern," from Latin crypta "vault, cavern," from Greek krypte "a vault, crypt" (short for krypte kamara "hidden vault"), fem. of kryptos "hidden," verbal adjective from kryptein "to hide," which is of uncertain origin. Comparison has been made to Old Church Slavonic kryjo, kryti "to hide," Lithuanian kráuti "to pile up." Beekes writes that krypto "is formally and semantically reminiscent of [kalypto]; the verbs may have influenced each other." For this, see calypto-. But he adds, "However, since there is no good IE etymology, the word could be Pre-Greek." Meaning "underground burial vault or chapel in a church" is attested by 1789.