What is "naked mollusk"

Naked \Na"ked\ (n[=a]"k[e^]d), a. [AS. nacod; akin to D. naakt, G. nackt, OHG. nacchot, nahhot, Icel. n["o]kvi[eth]r, nakinn, Sw. naken, Dan. n["o]gen, Goth. naqa[thorn]s, Lith. n[*u]gas, Russ. nagii, L. nudus, Skr. nagna. [root]266. Cf. Nude.]

1. Having no clothes on; uncovered; nude; bare; as, a naked body; a naked limb; a naked sword.

2. Having no means of defense or protection; open; unarmed; defenseless; as, naked to invasion.

   Had I but served my God with half the zeal I served my king, he would not in mine age Have left me naked to mine enemies.
   --King Henry VIII., Act iii. sc. 2 (Shakespeare)

   Thy power is full naked.
   --Chaucer.

   Behold my bosom naked to your swords.
   --Addison.

3. Unprovided with needful or desirable accessories, means of sustenance, etc.; destitute; unaided; bare.

   Patriots who had exposed themselves for the public, and whom they saw now left naked.
   --Milton.

4. Without addition, exaggeration, or excuses; not concealed or disguised; open to view; manifest; plain.

   The truth appears so naked on my side, That any purblind eye may find it out.
   --Shak.

   All things are naked and opened unto the eyes of him with whom we have to do.
   --Heb. iv. 13.

5. Mere; simple; plain; as, the naked truth.

   The very naked name of love.
   --Shak.

6. (Bot.) Without pubescence; as, a naked leaf or stem; bare, or not covered by the customary parts, as a flower without a perianth, a stem without leaves, seeds without a pericarp, buds without bud scales.

7. (Mus.) Not having the full complement of tones; -- said of a chord of only two tones, which requires a third tone to be sounded with them to make the combination pleasing to the ear; as, a naked fourth or fifth.

   Naked bed, a bed the occupant of which is naked, no night linen being worn in ancient times.
   --Shak.

   Naked eye, the eye alone, unaided by eyeglasses, or by telescope, microscope, or other magnifying device.

   Naked-eyed medusa. (Zo["o]l.) See Hydromedusa.

   Naked flooring (Carp.), the timberwork which supports a floor.
   --Gwilt.

   Naked mollusk (Zo["o]l.), a nudibranch.

   Naked wood (Bot.), a large rhamnaceous tree ( Colibrina reclinata) of Southern Florida and the West Indies, having a hard and heavy heartwood, which takes a fine polish.
   --C. S. Sargent.

   Syn: Nude; bare; denuded; uncovered; unclothed; exposed; unarmed; plain; defenseless.