[1] : The Collaborative International Dictionary of English v.0.48

pen \pen\ pe^n, n. oe. penne, of. penne, pene, f. penne,
   fr. l. penna.
   1. a feather. obs. --spenser.
      1913 webster

   2. a wing. obs. --milton.
      1913 webster

   3. an instrument used for writing with ink, formerly made of
      a reed, or of the quill of a goose or other bird, but now
      also of other materials, as of steel, gold, etc. also,
      originally, a stylus or other instrument for scratching or
      graving.
      1913 webster

            graven with an iron pen and lead in the rock. --job
                                                  xix. 24.
      1913 webster

   4. fig.: a writer, or his style; as, he has a sharp pen.
      "those learned pens." --fuller.
      1913 webster

   5. zool. the internal shell of a squid.
      1913 webster

   6. etymol. uncertain. zool. a female swan; -- contrasted
      with cob, the male swan. prov. eng.
      1913 webster

   bow pen. see bow-pen.

   dotting pen, a pen for drawing dotted lines.

   drawing pen, or ruling pen, a pen for ruling lines having
      a pair of blades between which the ink is contained.

   fountain pen, geometric pen. see under fountain, and
      geometric.

   music pen, a pen having five points for drawing the five
      lines of the staff.

   pen and ink, or pen-and-ink, executed or done with a pen
      and ink; as, a pen and ink sketch.

   pen feather. a pin feather. obs.

   pen name. see under name.

   sea pen zool., a pennatula. usually written sea-pen.
      1913 webster
see also:
cob bow pen bow-pen dotting pen drawing pen ruling pen 
fountain pen geometric pen fountain geometric music pen 
pen and ink pen-and-ink pen feather pen name name 
sea pen sea-pen 

[2] : WordNet (r) 2.0

sea pen
     n : fleshy featherlike warm-water colonies

Aegean Sea >> A Words
Aegean Sea, definition of term: Aegean Sea
aegean+sea_pag1.html

Adriatic Sea >> A Words
Adriatic Sea, definition of term: Adriatic Sea
adriatic+sea_pag1.html