'Sea slug' definitions:

Definition of 'sea slug'

noun

Any of various marine gastropods of the suborder Nudibranchia having a shell-less and often beautifully colored body [syn: sea slug, nudibranch]

From: GCIDE

Sea slug \Sea" slug`\ (Zool.) (a) A holothurian. (b) A nudibranch mollusk. [1913 Webster]

From: GCIDE

Slug \Slug\, n. [OE. slugge slothful, sluggen to be slothful; cf. LG. slukk low-spirited, sad, E. slack, slouch, D. slak, slek, a snail.]
1. A drone; a slow, lazy fellow; a sluggard. --Shak. [1913 Webster]
2. A hindrance; an obstruction. [Obs.] --Bacon. [1913 Webster]
3. (Zool.) Any one of numerous species of terrestrial pulmonate mollusks belonging to Limax and several related genera, in which the shell is either small and concealed in the mantle, or altogether wanting. They are closely allied to the land snails. [1913 Webster]
4. (Zool.) Any smooth, soft larva of a sawfly or moth which creeps like a mollusk; as, the pear slug; rose slug. [1913 Webster]
5. A ship that sails slowly. [Obs.] --Halliwell. [1913 Webster]
His rendezvous for his fleet, and for all slugs to come to, should be between Calais and Dover. --Pepys. [1913 Webster]
6. [Perhaps a different word.] An irregularly shaped piece of metal, used as a missile for a gun. [1913 Webster]
7. (Print.) A thick strip of metal less than type high, and as long as the width of a column or a page, -- used in spacing out pages and to separate display lines, etc. [1913 Webster]
Sea slug. (Zool.) (a) Any nudibranch mollusk. (b) A holothurian.
Slug caterpillar. Same as Slugworm. [1913 Webster]

From: GCIDE

Trepang \Tre*pang"\, n. [Malay tr[imac]pang.] (Zool.) Any one of several species of large holothurians, some of which are dried and extensively used as food in China; -- called also b[^e]che de mer, sea cucumber, and {sea slug}. [Written also tripang.] [1913 Webster]
Note: The edible trepangs are mostly large species of Holothuria, especially Holothuria edulis. They are taken in vast quantities in the East Indies, where they are dried and smoked, and then shipped to China. They are used as an ingredient in certain kinds of soup. [1913 Webster]